The engine seems to be running smooth (no change in rpm) but when I'm sitting still the whole jeep shakes???? What could be causing this?

 

whats the rpm's doing at idle?
Is your harmonic balancer very wobbly? (have a look: motor running, lift hood, look down behind radiator to the big pulley spinning, the big one way down)

 

its running right about 750 and yes there is a bit of wobble. Could that be my problem?

 

A little walking back and forth is not unusual.

I would check the motor mounts first. If they show any wear or cracking, replace them with quality new ones.

The polyurethane ones will transmit more vibration. Get rubber ones like OEM.

 

THe HB going out can cause some ' resonance'.

When I replaced my transmission mount and engine mount, there was actually more vibration then with the shot mounts, since everything was connected again, lol.