1983 911SC temperature problem
 

After driving my car for 30+ minutes and only when the engine is well warmed up will start to jerk while I am driving. This will occur in any gear and if I do not shut down the engine, it normally will die at idle. It is not until the engine cools down that it will start and drive normal. I have had the following done, new distributor cap and rotor, new plugs, valve adjustment within the last 2000 miles. The car runs perfect when cool, but I am able to repro consistently after the car warms up. Any ideas?

If CIS car, check for vacuum leaks, and the aux air regulator (routes air around the throttle) it should be closed when hot. Also WU regulator for correct fuel pressure when hot. Check sensor plate for oil and/or dirt/grime... clean and adj. if necessary. Check timing and advance too. Something will rear it's head.

My $ is on a vacuum leak.