Noise??

[AJV]

I recently bought a 1997 IDI jetta, and have found that under load there is a sort of thumping noise that sounds rotational ( driveline). It increases speed of thumping as the vehicle speed increases, it is more intense the larger the load ie. harder acceleration and it is also having a roughness, like a vibration. At cruising speeds (any) holding it at the speed, it is smooth. I looked at the drive shafts but found no rubs. I think the engine mounts are worn, especially the front one. Could that be it?  the engine moves too much? any help would be appreciated.
AJV

[Runt]

My first thought is CV's.  I'd throw it on a hoist (or jackstands, but I get to use a hoist so...  )  and feel if they have any play or movement in them.  I've seen some that would actually wear right out, not make the ugly turning whoompwhoomp (which is the outer end, fails most often) but when held by the axleshaft right at the cv, you could grab and move the shaft a fair bit rotationally, and sometimes side to side too.  This is more commonly the inner joint. 
Other than that, I'm assuming that you have already looked for bad tires (flatspots/broken bands/bulges), bent rims, wheel balance, etc.  Worn engine mounts sometimes make noise, but almost never cyclical noises in my experience.
Good luck.

[AJV]

I tried moving the cv shafts with a pry bar from side to side but I did not notice any movement, the boots are not ripped either. thanks for your help!

[Rabbit on Roids]

I tried moving the cv shafts with a pry bar from side to side but I did not notice any movement, the boots are not ripped either. thanks for your help!

a ply bar is not grabbing the axle and giving it a good shake. if you cant detect a worn piece with your hands alone, it aint that worn then in my books. and then you arent putting any un necessary load on any of the oil or grease seals in the front end. really the only thing you need a pry bar for is to persuade the engine out of the engine mounts.

[AJV]

I tried moving the cv shafts with a pry bar from side to side but I did not notice any movement, the boots are not ripped either. thanks for your help!

a ply bar is not grabbing the axle and giving it a good shake. if you cant detect a worn piece with your hands alone, it aint that worn then in my books. and then you arent putting any un necessary load on any of the oil or grease seals in the front end. really the only thing you need a pry bar for is to persuade the engine out of the engine mounts.

I tried by hand first and there was no movement so then I went to the pry bar.