Took it to a 3rd shop and he put it on the life twice and took it for serveral drives...and he said...not the transmission....more like a grounding out or electrical problem. Excepted we can't see where.....only does it in 1st and 2nd when gassing it good....under normal driving it's fine. He checked the motor mounts and the trans mount and all was good. This is getting boring! Want it fixed..... What to check next?

I am having the same probelem. The Jeep really seems to strain under hard acceleration but it seems as soon as it shifts gears or I let off the gas it stops. Although this does keep me off the skinny pedal ( and save me a couple MPG's ) I would really like to know whats causing it.

My problem was/is motor mounts and the trans mount will be changed at the same time.
Sometimes it is hard to tell if a mount is bad just by looking at it. You may have to stress it somehow to make the problem display itself. Or just take them off and inspect.

I am going to do some year down inspections this weekend ... if I figure anything out I will post it up. I think the motor and the tranny mounts are a good place to start !

Well, after my inspection the only thing I can see that was out of the ordinary was the driver side rear shock leaking. Its not likely the shocks would cause this issue is it ? I am going to get them replaced this weekend. Will post the results.

Boy am I glad somebody brought up this weird and quirky issue. My '99 has been doing this for at-least the last 5K miles. It's as hard to describe as it is to find. Whatever it is, it has also cost me as much as 4 mpg's. It sort-of has a "groan" to it under light acceleration and the rolling resistance just feels "off" because it used to coast easily but now it seems to slow significantly when I lift off the go pedal - as if dragging an anchor. I took a huge risk when I put the Jeep up on four jack stands and climbed under with all four wheels spinning unchecked (at idle RPMs) because I thought an axle or wheel bearing was chowed and I wanted to pin-point it. No dice, still trying to identify the source...

Ive been getting a vibration when accelerating. Ill have to look at my mounts. I was thinking my ujoints might be binding or going bad. I just bought my XJ and its got a mild suspension lift. Dont know how much lift but ive read even a 2" lift could cause probs with ujoints

I don't know if what I have is the same thing but I get a heavy vibration noise and feel at acceleration from the front drive train. My front drive shaft can be twisted by hand about a half inch or so when parked. The rear drive shaft is solid, no give when parked. I was wondering if this could be the issue? I would think that a broken engine or trans mount would be a heavy clunking noise, not vibration.

Did you ever figure out what that growling was? I have the exact same problem.