my 94 x300 starts on buttom and idles at 800 rpm but as soon the coolant temp increases so does the rpm to 1400.I cleaned TBbut no fix If unplug MAF the engine stalls. Could at the Coolant temp sensor?any suggestion welcome.

 

Lots of info on the problem.

 

That makes sense. When you’re engine is cold, it runs off of a preprogrammed air/fuel map until the engine is warmed up, then it switches to various sensors to tell it how to adjust the air/fuel ratio.

What is going on sounds like a vacuum leak. Air is getting to your engine which is coming in past the MAF sensor. Can you check around and see if any hoses have come loose?

 

I agree with Vee. The high idle issue is a recurring theme with these cars, and you will find a wealth of material in numerous threads in this forum. You havent mentioned whether your car is supercharged or normally aspirated, and whilst I have yet to see an idle issue attributable to the supercharger, its assorted plumbing makes tackling idle problems much more difficult.

 

Coolant Temp sensor is a $20 part and should take you 5 minutes to replace.