Jeep thumping

I have a 1988 jeep cherokee laredo i just bought and it was fine driving it home from the guy I bought it from, but then i tryed to drive it the other day and it was thumping everytime i accelatrated. I could coast no prob, but every time i put on the gas the thumping would shake the car... I haven't a clue what it is... Any ideas? :banghead:

Where Does the "Thumping sound" come from?
The front or rear or right underneath?
Can you feel it in the steering wheel or on your feet?
Does it sound like a knock or sound like someone stomping on a wood floor thud??

Well, it's like a thump from the back when i accelerate and it's like a thump thunp that shakes the whole car... it feels like it's starving or that its like choking from the back though.. it's quite strange... yeah, kinda like someone is stomping the rear end, and i can't tell really where i can feel it for cause i can feel it from every where in the car

Have a look at the rear driveshaft. It should have 2 universal joints; one or both may be bad.

I would check the motor/tranny mounts. Open the hood and while in drive hold down the brake hard and give it gas, if the mount is broken the engine will rise up in the air.

Does anyone think it may be an injector? i mean when it thumps it kinda feels like sputtering, like it's starving or somethin....

I found more of the issues with it when i drove to work today. it doesn't thump in first or second but between 2 and third, it starts thumping, and only when i put the gas on, if i only tap the gas, it doesn't do it... and then let up and tap, but i still would like to know whats going on! i just don't get it!!

Okay figured it out, it was the injectors. All better thanks ya'll