My 94 g200 is having idling issues, it starts by idling high then after a bit it starts to fluctuate, Can’t work out what us casuing it. Turning on the ac makes it run normal and while driving it runs normal. I can hear a sucking noise coming from somewhere and when it revs higher it blows smoke that smells like fuel.
sounds like an air pocket in the cooling system with the idle issue.
Maybe a vacuum leak? I’d check the cooling system first though.
I bled the system of air but it didn’t solve the issue
I had the same problem in my m300. The problem for me was a vacuum leak in both hoses coming from the airbox to the throttle body. Maybe you have a similar problem?