What was going on when I was born?

The decision by Federal authorities to ease the fuel economy standards for the domestic automobile industry is not likely to revive the gas guzzlers of old, although it may delay the introduction of more efficient models. The Department of Transportation lowered earlier this month the average fuel economy figure that must be met by each company's cars to 26 miles to the gallon, from 27.5 miles, for the 1986 model year and possibly for three years more. This will give the General Motors Corporation and the Ford Motor Company a lift in profits by permitting them to sell large rear-wheel-drive cars of older design for a few more years until they are replaced by more efficient models. Officials at Chrysler, which has discontinued most of its larger models, estimated that large cars account for $8 billion a year in profits for General Motors and $3 billion for Ford.

The Long Island clamming industry, once the nation's leader, has fallen into a decline that some experts fear could lead to virtual extinction. ''This is a dead industry in five years,'' said Lee Koppelman, executive director of the Long Island Regional Planning Board, ''unless we get proper bay management.'' The bleak forecast is based on studies done for the planning agency by marine scientists. Hurt by a shortage of clams, shaken by falling consumer confidence in the safety of eating raw shellfish, the $100 million industry of the 1970's has shrunk to less than $40 million. Long Island has fallen behind Rhode Island and Florida; even its own restaurants and fish markets have begun selling clams from out of state.

Missing text YANKS ROUTED, 8-2

When Robin Leigh-Pemberton succeeded the widely respected Gordon Richardson as governor of the Bank of England two years ago, the City of London rippled with privately expressed qualms, and newspapers wrote unenthusiastic editorials. To be sure, the National Westminster Bank had flourished under the amiable Mr. Leigh-Pemberton's six-year stint as chairman, but that was a job that centered on general policy making and external relations. Skeptics wondered whether it had provided Mr. Leigh-Pemberton with enough experience for the governorship of Britain's central bank - a banking position commonly described as the world's second-most demanding and influential, after that of United States Federal Reserve Board Chairman Paul A. Volcker. The governor of the 291-year-old Bank of England, which was nationalized in 1946, is answerable to the Chancellor of the Exchequer, and thus less independent than Mr. Volcker. But the governor is also, by tradition, the informal czar of the City, London's financial district, and involved with the welfare of a far broader range of financial institutions than his American counterpart.

HOW does Harry Rothman do it? That is the question that, as the radio commercials say, incredulous New Yorkers have been asking themselves for decades. Now the mystery has deepened. The discount clothing store on lower Fifth Avenue has slashed its prices even more, and the refrain is, ''Why is Harry Rothman, the dean of men's wear discounters, doing this?''

In the two decades since American computer companies began seeing a market in every office, factory and home, this city of world-class research has blossomed into a center of world-class manufacturing. But the computer revolution has stalled. And Boston, which has emerged as one of the nation's strongest urban economies, is wondering where to look for its future growth. ''The computer industry was growing so fast there had to be a shakeout,'' said Gov. Michael S. Dukakis. Fred Wang, the executive vice president of Wang Laboratories Inc., added that ''this industry is in a tough transition.''

On the day after they scored 23 runs in a doubleheader, the Mets sort of rested yesterday. And except for Darryl Strawberry, who knocked in all their runs with two home runs, they were tamed by 40-year-old Joe Niekro and his knuckleball and overpowered by the Houston Astros, 12-4. That was good for the Astros, because they had lost six straight games and 12 of their previous 13, and their offense had not been seen for at least two weeks. But it was bad for the Mets because they stumbled after winning three straight from the Astros and, more to the point, because Ron Darling suffered his briefest and worst start of the season and lost for the second time in a row.

An article on the Washington Talk page July 17 about paintings in the Capitol misidentified a painter and incorrectly attributed all paintings in the building's Rotunda to him. There are eight paintings there, four by John Trumbull and four by other artists.

The Defense Department has made what it calls an ''unprecedented decision'' to allow civilian doctors to monitor systematically the quality of care administered in the military health-care program, a Pentagon source said today. Under the new monitoring system, scheduled to go into effect no later than Jan. 1, civilian doctors would review the records and care given to about 15 percent of the patients admitted to military hospitals. They would pay particular attention to cases in which problems are most likely to arise.

Orders for American-made machine tools rose 5.5 percent in June from May and jumped 22.6 percent from their June 1984 level as the industry continued to rebound from the disappointing levels of orders and shipments earlier in the year. According to a report to be released today by the National Machine Tool Builders' Association, machine tool makers booked orders valued at $235 million in June, from $222.7 million the previous month. Orders in June 1984 were valued at $191.7 million. Shipments in June soared 34 percent, to $237.6 million, from the previous month's level of $177.3 million. The June shipment level represented a 16.8 increase from the June 1984 level of $203.5 million.

Going to the Hamptons can be wonderfully pleasant, of course, if you can't arrange to stay in the city on weekends. ''Everybody who's anybody knows it's hipper to be where everyone else is not,'' said Mauri Cramer, a 25-year-old dancer who was happily on the Upper West Side on Saturday. ''You have no one to blame but yourself if you went to the Hamptons,'' agreed Chip Brown, a 32-year-old writer. Those who engage in the Friday flight to the shore and the mountains smugly assume that they leave behind a steamy, boring husk of a city, peopled by tourists, suburbanites and frustrated residents who must stay because they have to work or because they have not been invited to a vacation refuge. But it is one of New York's best kept secrets that many who remain savor the city on summer weekends and say they discover a side to it that cannot be experienced at any other time.

International Japan will announce market-opening measures tomorrow, but few think they will do much to stave off increasing calls for retaliatory measures. The U.S. wants Japan to make substantial economic changes to deal with its growing trade imbalance, but such ideas encounter powerful opposition in Japan. [Page A1.]