lots of vibration
 

to start off i searched this forum couldnt find anything next i have a 91 s5 n/a no mods welded diff and today i went out to drive my car and i had a nasty vibration right around 2k-3k rpm's in 3rd,4th,5th gear but once i get to about to 3500 it seems to straighten itself out again i have read that it may be my secondaries just not kicking in but i also might think its my fuel pump it is whining i know its on its way out but lmk what you guys think

:suitdancecheck driveshaft my b time to change it

yea maybe there is also some serious clunking if i back out of the throttle all the way andget back into it

Injectors or fuel pump? Not going to be related. You're looking for a mechanical issue in the drive-line or with a belt driven accessory.

http://www.mazdatrix.com/g2.htm

motor mounts possibly???

Check tranny mounts