The House ethics committee, already burdened with public criticism and internal dissension in its effort to investigate South Korea influence-buying in Congress, has run into the barbed political wit of cartoonist Garry Trudeau.

Off and on for the past three weeks, characters in Trudeau's syndicated "Doonesbury" comic strip have been poking fun at the pace, seriousness and possible hypocrisy of the committee's efforts to get their probe on track. And not all committee members, who have become quite concerned with their public image of late, are laughing along with Trudeau.

Yesterday, for example, Rep. Floyd Spence (R.S.C.), ranking minority member, said he critieized one of the recent "Doonesbury" strips at an informal meeting that the committee held Wednesday to discuss how "to improve the image of the investigation."

"That fellow now, what does, he know about the progress of our investigation?" Spence asked. "We don't have a PR firm to defend the committee and it's very frustrating to have to deal with the misconceptions people get from reading something like that cartoonist."

Spence said a woman from Washington state nailed him a copy of a "Doonesbury" strip as an example of her anger at what she considered the slowness of the committee 's pace in investigating members who took cash or gifts from the South Korean government.

She doesn't understand, and neither does that cartoonist, that we can only go as fast as our investigators let us," he said. "And they're doing a very thorough job."

Others involved in the committee's inquiry found the recent"Doonesbury" references more amusing.

Committe member Millicent Fenwick (R.N.J.), for instance, bears a "Doonesbury" character Lacey Davenport, who also just happens to a "member" of the committee.

Frenwick said yesterday that she doesn't read the comic pages and hadn't noticed the striking similarities between herself and Davenport until a reporter asked her about it. "But I think it's marvelous. After all we have to be able to laugh at ourselves a little in this business," she said.

Hollis McLoughlin, her administrative assistant, said yesterday that the staff has been clipping the Lacey Davenport strips for some time and have several hung on office walls. "She (Fenwick) never noticed until she was asked about the ethics committee-Korean reference," he said. "We've been cracking up for months."

In this week's strips, "Rep. Davenport" is in the midst of hiring recent law school graduate and longtime "Doonesbury" hero Joanie Caucus as a committee investigator.

Anticipating that possibility, Philip A. Lacovara, the committee's special counsel for the South Korean investigation, wrote a tongue-in-cheek letter to Trudeau yesterday, asking for copies of Caucus' resume and references. Lacovara said in the letter tha he was interested in learning more about Caucus' qualifications, even though she didn't seem to have the experience he was looking for in his staff.

"I can afford to take the 'Doonesbury' strips good-naturedly," Lacovara said. "I can see how some member might not and might consider them bad publicity.

Wednesday's unannounced meeting of committee members was the latest sign of how serious the ethics panel considers its image problems.

Without staff or investigators present, some members who attended said, they hoped to thresh out among themselves a way to handle mounting criticisms.

Rep. Lee Hamilton (D-Ind.), who called the meeting in his office, said the session wasn't secret but he didn't feel free to discuss it because the members reached no conclusions, and made no decision on what to tell the press.

Others present said they talked about how to handle what some consider unfair press reports about the committee's pace and sincerity, as well as the increasing pressures for action being brought by younger members of the House.

Spence, for instance, referred to the "Doonesbury" strip and a wire service report of a May 12 committee meeting where members refused to sign an oath that they themselves had taken nothing from South Korea or any othe government.

The day of tha meeting, The Washington Star carried a front-page story questioning whether the 12 committee members were untainted themselves so they could judge their colleagues impartially.

The same day, Trudeau's "Doonesbury" strip featured "Rep. Davenport" being asked how many members of the committee were involved in the scandal. "Cynical question, Four," was her reply.

More recently, fiedgling lawyer Caucus likens five months of duty on the ethics committee staff as unfair for her reporter boy friend to ask to match his five-month stint as West Coast "divorce editor" for People magazine.

How far Trudeau intends to carry his version of the committee's investigation is unknown. He could not be reached for comment yesterday.