An Air Force plan to move its 401st Tactical Fighter Wing from Spain to a planned new NATO base in Crotone, Italy, ran into new problems yesterday when the Senate Appropriations Committee directed the service to develop "lower cost alternatives."

However, in approving a 1991 military construction appropriations bill, the committee stopped short of Monday's House action barring all funding for the base.

The F-16 fighter wing has been told by the Spanish government to vacate its Torrejon base by May. On Tuesday, the House Armed Services Committee in effect ordered the wing to return home. But the Senate committee declared that "an F-16 presence in southern Europe is important," and called on the Air Force to consider a no-frills "minimum cost" facility in Italy.

"If the Pentagon refuses, Crotone is probably dead," a congressional source said.

The Senate bill sharply cuts spending on bases in Europe and Korea but hikes funds even more than the House-passed bill for reserve and National Guard bases at home.

Meanwhile, the Senate committee sought to avoid involvement in a dispute between two of its members. Sen. Pete V. Domenici (R-N.M.) is supporting relocation of the F-117A "stealth" fighter wing from Nevada to Holloman Air Force Base in his state. But Sen. Harry Reid (D-Nev.) wants to keep the wing in Nevada. The committee deferred granting $11 million to upgrade Holloman pending a study.

Despite concerns about soaring budget deficits, the committee also approved a $20.7 billion Treasury and Postal Service bill containing numerous projects for home states of committee members.

General Services Administration accounts were funded for a $4.3 million grant to Midwest Supercomputer Access Center in Ames, Iowa, home state of Democratic Sen. Tom Harkin, a candidate for reelection. The same bill funds an $80.4 million federal building in Charleston, W.Va., in Appropriations Committee Chairman Robert C. Byrd's state.