I am having this exact problem. Except my car is a 95 SL1 and a manual. I’ve done all of the same stuff.
Cleaned the throttle body, replaced pretty much all the sensors, checked for leaks… It happens when the a/c is off or on.
Sometimes when it levels out i can turn on the lights, or the blinker, or hit the breaks, or anything that uses more electricity and it starts idling rhythmic again.
Also i replaced the alternator to the 105amp and it didn’t help. As well as the PCM and ICM
[video]https://www.youtube.com/watch?v=mtyz5Y8flkY[/video]