If I am stopped at a light, the vibrations/shaking are so great that it shakes my keys. But if I lightly tap the gas, the vibrations stop. I don't notice any vibrations in Park...only when I am in gear and stopped. The RPMs stay at exactly 700 the whole time. I took it to the dealership and they claimed the engine mounts are fine and the idle speed is fine... they basically said they don't know what is wrong and sent me home without charging me. I've recently cleaned the throttle body (this helped the RPMs to normalize at 700), changed the spark plugs, and changed the timing belt, but none of this has helped with the vibration. A common suggestion online seems to be to clean the idle air control valve, but I don't seem to have that in my V6? Any ideas on what I should try?

 

The vacuum chambers in the mounts are supposed to soften up when idling ..... that might be the problem, that the mounts remain stiff. Also, next time it happens, try turning off the AC. Also, check your air filter.

 

Air filter was recently changed so I know its not that

I did check today and the vibration is much worse when the A/C is on. But when the A/C is off, there is still some vibration of the keys...its just not as bad (maybe 1/2 as bad)

 

I'm thinking rear lower engine mount or a vacuum leak. Those engine mounts are pretty weak. Before I killed my tranny, I had replaced 3 of the 5 and the ones that weren't completely destroyed were still a lot softer than I'd want.

 

I guess I could buy a vacuum gauge and test for a vacuum leak?

But for testing or replacing the engine mounts, is that something easy enough for a DIYer or do I need to take it to a mechanic? I was looking in the service manual, but it is always geared towards dealers/mechanics with the $$$ diagnostic system ("press 1 to turn on/off engine mount solenoid")

 

Tough for me to say .... I've done most stuff myself, but in the past couple years I either don't have time or are just too lazy to do some things myself ..... that's where my buddy takes over. He's a master machinist ..... I haven't seen much that he can't do himself.