Installed energy suspension mounts but...

I recently bought this '90 mustang GT. Its pretty nice, but it had a shakey motor, if you're driving it in second at low rpm and you blip the throttle, something internal feels like its rocking back and forth slamming at the front and back of its rocking strokes. So I installed the energy suspension engine and tranny mounts, I still get the same thing shifting engine effect but it is much less pronounced now. I bought the crossmember bushings but decided not to install them yet cause my current bushings seem to be solid (and the H pipe is in the way). Have any of you experienced this shifting back and forth of the engine? Any help would be greatly appreciated!

sweet man, I'll try that out and tell you if I find anything!

My stock headers do seem to have a dent in them right near the steering shaft. But its a bit of travel. Not sure when that happened. As far as frame mounting bolts, the two bolts behind each wheel seem to have clean spot around them(the rest of the area is dirty) so I know theyve moved. They seem to be pretty darn tight though, I loosened them with a breaker bar and then tightened em back up again. Not sure if thats the problem. The two bolts up by the top of the spring seemed tight too. Are these the frame bolts you were talking about?