Motor rucksacks in stationary gas

Hello, everybody.

I have already read a lot about this problem in the forum, but I would like to describe and ask for advice.
So I had my '89s 3.6 in the workshop converted to EURO2 a few days ago. Now I drove into the wash road and had a wash under the floor. After that, the shit started. Engine was warm. On the road in urban traffic. Suddenly at the traffic light on "D" in the stationary gas restless engine noises. Like he's about to strangle himself. After a little while, it started again, at the next traffic light. And he didn't pick it up right away when he was gasping, and it took a few seconds for him to come and finish. It came and went again and again. He also went out twice, but jumped back on immediately, so the whole thing went on all day. Also in the positions "R" and "N". ==References====External links== on highway, was nothing. So always in the lower speed range. Then yesterday he was back in the workshop, trying to find out about error reading, but he didn't come in. Had a communication error (new software on ́m computer) Then removed the plug from the control part of the EURO2 cold running controller, then replaced the LLRV...nix. For reasons of time it could not be searched further, but further conjectures were throttle flap poti, engine control part etc.
Before the conversion to EURO2 it was not so yet. So maybe that's what it's all about.
I don't know if it was in cold conditions, but definitely in a warm state.
I think I should've let the underbody wash be. You want to do something good and then shit like that. It's like women... how you do it, you do it wrong.
Are we on the right track - "Rosselklappenpoti maybe", speed sensor?
Or Lambda probe? It's new.
I hope you can help me and thank me in advance for your advice.