Clutch chatter problem

[oldsgmc]

Had a new clutch installed in my truck a while back. At the time replaced the slave cylinder, new disk and cover and had flywheel redone. Result was a slight chatter. Few weeks ago had the trans rebuilt and had the shop put in a new clutch and another resurfaced flywheel. Has chatter but it comes and goes. Now the throw out beiring is making noise. and that as well comes and goes.

could this be caused by bad motor mounts?
The chatter comes and goes and now im at a loss what this could be, any suggestions would be appreciated.

1997 gmc 2500 350 with NV4500 170K miles

Thanks for any help