AFTER ALL HIS TALK about holding down municipal spending and paying off years of accumulated deficits, Mayor Barry continues to play yo-yo with gasoline taxes--up and down, according to what the political and pumpside traffic will bear. This week, he is asking the council to repeal a one- cent increase scheduled to take effect June 1-- which would mean losing a projected $2 million in additional revenue over the next year and a half. He should leave well enough alone.

This is the third time the mayor has asked for some kind of reduction in gas tax increases that his own administration originally backed. The trouble began with Mr. Barry's ill-advised insistence on an 8-cent increase in the tax, which was too much in one swoop. It was that jump that did drive a statistically noticeable number of motorists to the suburbs for gas, helped put some station operators out of business and finally led to repeal of the increase.

Then came a scheduled 2-cent increase in the tax, followed last year by a request from Mayor Barry to halve it, which the council wisely rejected. That is what the council should do this time, too--even if it goes against the campaign grain of members running for re-election or for mayor. In the face of so many austerity policies, it would be inconsistent for city hall now to shrug off additional revenue for what surely would be a short-lived improvement, if any, in the competition with suburban gasoline taxes and pump prices.

Already, Northern Virginia is preparing for an increase of about 4 cents a gallon in July, bringing the total state and local taxes to about 17 cents a gallon. Maryland's tax is scheduled to rise in June from 9 cents to 11 cents. With the city's next scheduled increase in effect, the tax would be 14 cents a gallon. These regional differences are by no means as great as those caused by Mr. Barry's original tax policy and should not result in the same alarming exodus of District motorists to suburban gas stations.

Besides, whatever political benefits may have been thought to accompany this latest repeal proposal are likely to disappear in the face of resulting skepticism about the mayor's determination to keep reducing the city's accumulated debt. And if Mr. Barry can't think of anything to do with the additional money that the scheduled increase would generate, surely motorists could find him a few low spots in the highways and byways of the city that could stand some filling. The city's coffers could stand some filling, too. Repeal of the scheduled increase would be an unsound decision.