Vibration In Gas Pedal

[threepwood]

I have a 1992 LS400 (140k miles). Several months ago i began feeling a vibration in the gas pedal during acceleration. Almost like a resonance. It would be there for a week, then go away completely. Now, the vibration is there all the time. In neutral, there is no vibration until 3200 rpm, and then it is a real shake which goes away above 3500 rpm. Everything I've read here points to engine/transmission mounts. I removed the transmission mount and it looks fine. Is there some way to test these mounts before I spend a lot of time & money and don't fix the problem? Is there anything else I should be considering?

Thanks.

[jcrome04]

Possibly a bad spark plug or two not firing right??? Engine mounts would seem like the most likely coulprit to me. Maybe clean your throttle body and seafoam? It sure smoothed out my engine...

Not sure about these, but just trying to get some ideas going... :whistles:

[threepwood]

Possibly a bad spark plug or two not firing right??? Engine mounts would seem like the most likely coulprit to me. Maybe clean your throttle body and seafoam? It sure smoothed out my engine...

Not sure about these, but just trying to get some ideas going... :whistles:

Funny you should mention throttle body because when it first started I put fuel injector clearner in it and i thought it went away. The second time i did the same thing and it seemed to go away, but when it started the third time and didn't go away after adding fuel injector cleaner i assumed it was my wishful thinking that it wasn't engine mounts. By seafoam do you mean air cleaner?

Thanks