I had this trouble with my 240/300na car. I had installed a cheapo cisc from autozone along with a new pp from the factory. I also had a loose motor mount on that car for a long time before we found a broken allen on the bottom of one motor mount.

I think the mm bolt may have contributed.

Also some clutch disc friction material might draw moisture after sitting a while....my 72 bmw drum brakes did this and woud be grabby until warmed up.

I would just change my taking off habits until it quits....maybe giving a bit more gas and slipping it a bit, until the clutch disc wears down a bit...

oh and always buy a factory clutch disc too.

Tom W

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.