So my friends 95 Cobra(5.0) engine shakes pretty bad @ idle, but as soon as you give it a little gas it goes away like there's not a problem. It idles a little high(a little over 1000rpms), until you start driving it around, then the rpms sit where they are suppost to sit, another weird thing is that when the engine is shaking @ idle, if you turn the a/c on, the shaking goes completely away...does anyone have any idea of what the problem is? anyhelp is great...thanks!

 

sounds like motor mount and the idle is just the correct rpm to make it shake the best when you turn the ac on puts a load on the motor so changes the rpm just enough to stop

 

+1 check the motor mounts.

 

...I was thinking the same thing!