Shudering on deceleration
 

When I'm slowing and rev's go under 2000 car starts bucking violently untill I take it out of gear. Also if I don't let the clutch out just right on aceleration it shudders sometimes as well. It has about 1000 miles on a fresh rebuild(2.7L) . Clutch had good thickness and the flywheel was redone. It feels like the motor mounts are loose but checked out ok. The old mounts were reused and looked ok.
Any ideas?

This sounds similar to a problem I have. If I accelerate at low revs (1500 - 2000) and then lift off, the car judders down to the natural, even RPM for the amount of gas I'm giving. I feels kind of like a sticking throttle. I have checked & replaced my return spring.