CONGRESS STANDS in imminent danger of losing its grip altogether on its investigation of Korean influence-peddling and of opening itself fairly to the charge of covering up.

In one step undercutting the investigation, the House International Relations Committee last week approved an administration request, pending for seven months, to transfer $800 million in arms to South Korea as American ground forces withdraw over five years. In a second step, Sen. Adlai Stevenson (D-Ill.) dropped objections to official financing of a $732-million nuclear purchase by Korea; earlier he had insisted that Seoul first provide suitable congressional access to certain nationals, notably former ambassador Kim Dong Jo. And on Wednesday the House rejected a bid to cut agricultural aid to South Korea despite a plea by Special Counsel Leon Jaworski that the House strengthen his hand in bargaining for Korean cooperation with the influence inquiry by making the cut.

Each of these steps has its reason. The arms transfers make security sense. The nuclear deal has a strong economic rationale. The agricultural measure came up under circumstances (in a budget resolution) and sponsorship (by Republican Rep. Bruce Caputo of New York) variously distasteful to members of both parties. A case can be made, moreover, that since Korea did induce rice dealer Tongsun Park to testify, the Congress owed Korea some response. The cumulative effect of these concessions by Congress is, nonetheless, to call into question its determination to clean house. In particular, investigators have yet to gain access to former envoy Kim Dong Jo, whom Mr. Jaworski has identified as critical - not merely because Mr. Kim, like Mr. Park, stands accused of giving money to congressmen but because Mr. Kim, unlike Mr. Park, is without question an official Korean agent. The Constitution specifically bars legislators from accepting gifts from foreign agents.

The conviction of one bribed congressman and the indictment of another have conveyed an impression that the influence investigation have done their job. Another impression is gaining that South Korea has been harassed long enough, and perhaps unfairly, and it is time to repair the important Korean-American diplomatic tie, the administration holds that view. Yet the reputation of the House, and of several dozen past and present members, and of its leadership, will remain under a cloud if the inquiry is not pressed further. Specifically, more must be done to obtain direct communication with Kim Dong Jo. If he does not choose, as he could, to waive the immunity that everyone agrees is due him under the Vienna Convention, then surely he can do better than offer a telephone interview with the speaker of the House. The House has several possible ways, by resolutions or action on legislation, to affect any Korean inclination to conclude that the heat is off. Otherwise, Mr. Jaworski, whose service depends for its effectiveness entirely on the cooperation of the group he is investigating, would seem to have no alternative but to explain why he is unable to pursue further, and still less wind up, an investigation that House leaders as well as members implored him to conduct. It would then be up to the voters to judge whether the honor of the House had been redeemed.