Terrible vibration problem
 

I've had vibration problems with my 2005 Mazda 3i. I have read various forums that said to change the motor mounts. Took it to the shop and got the passenger mount replaced, that's when the real problem began. After that one was replaced is when the major vibration started to happen. Shop then changed my transmission mount, problem still exists. They're clueless and think it could be something in the engine. I've read about the rear mount rarely going bad, but could that be the problem? I can feel the vibration throughout the entire front of my car, mirrors shake and the higher the rpm the louder the vibration/shaking. Also, is there a way of checking if the rear is the culprit without actually taking it off? Any info would be much appreciated, driving with that vibration has become highly annoying.

Change the rear mount as well. Hopefully this will take care of the problem.

Thanks for the replays. Problem has been fixed. It was the passenger motor mount that the garage told me they fixed in the first place, but obviously they didn't because that was the problem!