Whenever I accelerate in my 1991 5.0 Liter, the engine starts to shake, causing the entire truck to shake. But as soon as i step off the gas, the shaking stops. I can't seem to figure out what would be causing this problem? Has anyone had a similar experience, or can give an accurate diagnosis. Thanks

Tom

 

could be u joints, drive shaft out of balance, do you have a limited slip differential?

 

Broken motor mount?

 

I checked the motor mounts and they seem good, and the ball joints were JUST replaced. Not sure about any other joints. I was thinking more along the lines of something being unbalanced.

 

Sounds like not all cylinders are firing. How long since the last good tune up? How old are the plug wires? Coil? Cap? Got the engine real wet lately?
bullseye670.................