So, The PO told me about this before I bought it, and said it was U-joints. Well, after checking them all, they seem fine.

Basically, while cruising down the road at constant speed, there is an intermittent "clunk" like someting shifting under the car. you can feel it actually move the seat a bit as well. I know I need a tune up as there is a slight miss, and wheel bearings are good, so any other suggestions? I was thinking tranny mount as it will not do it if I am coasting down a hill. Only when I have a constant speed maintained....

 

Is the noise a front or a rear noise? Fronts can be anything from control arm bushings to swaybar to shocks. Rears may be spring eye bushings or shocks or swaybar.
It is going to require crawling under there and using a prybar to find the loose item.

 

Also have a buddy bounce the jeep up and down while you watch things..That's how I found issues on mine..

 

Well, shocks are all brand new, just replaced by the PO a few weeks before I bought it. I guess I will have to do some research underneath.

Thanks guys!

 

So a coworker suggested it could be a momentary loss of spark causing the engine to lurch while under load, and there was a slight miss at idle, so I though that may be the case. Did plugs, wires, cap, and rotor, and it still does it. The hesitation is gone for the most part, but still there some of the time.

I'm getting frustrated with the clunk though, and dont know what it is. I still think it's the tranny mount for some reason....just seems to be coming from the center of the car.

Oh well, more research to do!