Idle RPM
 

What is the correct RPM that the 2.5 m96 should idle at? Mine idles at about 800 and this seems low... lots of vibration. reasons this could be happening, fixes? thanks

Sounds normal. Even modern Porsches idle at this RPM, after they come of fast idle (1,200ish RPM about 60 seconds worth). Check your motor mounts.

750-800 RPM is normal for a warm engine.

If you have a rough idle which creates engine/body vibrations then look into idle issues (ICV, MAF, vacuum leak, dirty throttle body, misfire, etc)

If the idle is fairly smooth but you feel engine vibration in the body then look into mounting issues like motor or trans mounts.

800 is fine for a warm engine, it's when it gets over 1000 warm when you need to start looking for vacuum leaks and such.

On a side note, my E34 BMW idles at 637-642 rpm at idle when warm, it had a bad vacuum line on the EGR side that caused it to idle over 800 before I isolated and repaired it.

Clean your throttle body and MAF sensor. I'll bet that helps you out with your idle issues. Did for me.