Heavy Vibrations NEED HELP!

[97GSX88]

OK I have been searching around for the past week to try and find out some info on this but no luck really. My problem is when the car is in reverse it makes this heavy vibration that seems to be coming from the front of the car, however after I give it a lil gas and move the vibration stops. Not all the time but sometimes it will do this in drive when I come to a stop and/or put it in drive sometimes it will make a vibration not as heavy as when in reverse but still noticeable. I recently (2 months ago) replaced the end clutch and tranny oil and filter. After I did that it ran fine until about a week or so ago. Only thing else is I put on a Lightened Crank Pulley but I have checked it and seems fine. I really need some help on this one I usually can figure out wats wrong normally but this ones got me.

Thx
Chris

 

[robs90tsi]

Are your motor mounts tight on there?? Or they could be worn. I presume you have an auto, when you shift, your tranny and motor will twist, and if not properly secured, begin to vibrate horribly.