Back in January, Rep. Toby Moffett (D-Conn.) accused Environmental Protection Agency head Anne M. Gorsuch of giving preferential treatment to a small New Mexico oil refinery. Moffett claimed Gorsuch had promised the financially strapped Thriftway Co. that she would not prosecute the company if it began putting more lead than allowed by EPA standards into its gasoline.

Moffett called for an immediate investigation. EPA officials, meanwhile, accused Moffett of trying to grab headlines.

Yesterday, Moffett released copies of an EPA inspector general's report that concluded that Gorsuch did, in fact, promise she would not prosecute the company for violating the lead standard. The report said Gorsuch did not feel the promise was improper because EPA is in the process of reviewing the lead standard with an eye to relaxing it. The report did not give an opinion as to whether Gorsuch acted improperly.

Moffett said he has written a letter to President Reagan, charging Gorsuch with destroying "the agency's credibility" and corrupting "its enforcement effort."

EPA officials, meanwhile, once again accused Moffett of headline-grabbing. John E. Daniel, EPA's chief of staff, said the report was "a complete vindication" of Gorsuch's "involvement in a minor matter."