Engine vibration comes and goes

I have an 87 Cherokee 4.0L auto. The problem is it will sometimes vibrate at idle and will get worse when it shifts into 3 gear like it's hesitating(low RPM). But it's comes and goes. one minute it is good, next it's not.

Replaced Cap, Rotor, Spark plugs and wires.
Engine mounts are good.
Replaces Fuel Rail O-rings.
Replaced Fuel Filter.
Checked for vacuum leaks.

ANY IDEAS?

Has anyone had similar problems?

lgorman00 said:

Replaced Cap, Rotor, Spark plugs and wires.
Engine mounts are good.
Replaces Fuel Rail O-rings.
Replaced Fuel Filter.
Checked for vacuum leaks.

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did you check the trans-mount too?

seems like a sensor is goin bad..

check TPS, IAC ...