I have a 1989 i6 and the idle fluctuates after it warms up. Also the coolant temp gauge does not work. What is causing this and how do I fix it? I posted a video of it on youtube to help show the problem.


thanks, you have to listen to hear the engine, but you can see the needle moving

 

Almost always a Vac leak! A need to clean cleaning the IAC valve is my 2nd guess!