I've got the shakes!
 

So to get things started, I recently (this summer) purchased a 1988 Supra Turbo (117k miles), and so far it's been pretty sweet. Just about everything is still stock (although looking over the receipts I got from the previous owner, it seems that the radiator was replaced a few years ago).

However, when I start getting close to 3k RPMs (it's a manual, by the way, the problem seems to be at it's worst in 5th gear), I can feel the car start to shake. Once I get past the 3k mark, the shaking stops completely. It is something I noticed first in 5th gear, and it is progressively less noticeable in lower gears (can feel it in 4th, a little bit in 3rd).

So what do you guys think could be causing it?

~Kc

edit: Also - it seems to only be doing it when I've got my foot on the accelerator (and it'll stop immediately if I take my foot off).

sounds like something is off balance, mabey the fly wheel or crank balancer, it seems like it have to be on the engine.

Check your drive line. Possibly the center support bearing / bushing.

Does it only happen while your in gear? Say you are going 50mph and you put it in neutral, does it still shake? Could be you wheels being outta balance.