I have a 1991 rx7 that is making an odd grinding noise while coming down from rev, wether the clutch is in or not. If I rev at all it seems to go away but when it comes down it shakes and grinds, although it only does this when the engine is fully warmed up. I have recently replaced the clutch, throwout bearing and pilot bearings, the flywheel didnt look too bad but at the same time I couldnt get it machined due to a time constraint on the garage I was using. The other problem also only comes up after it is warmed up as well. It will hesistate, buck , and jerk pretty bad at high rev while I am driving. I can usually baby it and keep it below 3500 to get somewhere safe but I cant figure out what could be causing this :P

 

If the clutch isn't slipping, I'd say it was the clutch slave cylinder, but then I saw that you said it was bucking and hesistating... hmm...

 

Gonna replace the slave cylinder this week. The hesitating is apparently, mostly blown spark plugs . The first thing I should have changed . Lol