1992 Toyota 4X4 Truck clutch was working fine

1992 Toyota 4X4 Truck mileage: 117,000 miles. At about 100,000 miles, I had the original clutch replaced. The clutch was working fine, but because of the mileage, I felt it would need replacing soon. Since the truck would be spending some quality time at the Toyota dealership for the infamous head gasket problem, I felt this was as good a time as any. The Toyota dealer replaced the clutch, pressure plate, bearing, and turned the flywheel. The new clutch grabbed when starting off in first and especially in reverse. It feels like the clutch is chattering. I returned the truck to the dealer with the above complaints. They claim they replaced the clutch once again, but it did not cure the problem. At this point, they thought the recently turned flywheel needed replacing, naturally at my expense. After all this the truck still has the same problem, but less severe. If driven aggressively, the clutch works smoothly. The problem is most evident if you just release the clutch without applying the gas. My question is, what other conditions could cause this particular problem? Could the strength of the new clutch accentuate worn engine mounts? Would worn out bearings in the rear end cause this, and if so, how can you tell if the axle bearings are worn?