I think my xj has been idling slightly high possibly lately. Because shifting from reverse cause the truck the forcefully lurch forwards, even with your foot a little on the brake, you still fly forwards some while shifting from reverse to drive. It also seems to happen more often while the tranny is warm. Torque converter? I don't think my motor mounts are bad bc it doesn't show the "torsion" when revved. But does an inline engine do that anyways? Do only "v" configs twist like that when revved?

 

And the 2014 Cherokee commercial came on...

 

bad u joints?

 

High idle....Vacuum leak ?

 

Don't rule out the mounts either until you've done a visual inspection. Time for some "noggin pokin'".