'92 300E stalls, won't re-start warm

[prmichael]

I'm posting this because I've read through thread after thread of the same symptoms, some of which have been cured by OVP relay, CPS, distributor rotor, etc. usually after throwing a myriad of parts at the problem.

Working on a buddies '92 300E 334,000 miles. Replaced his fuel distributor a couple years ago (because the Benz dealer got it started with a new coil, but didn't fix the intermittant stalling problem) and it ran fine for a good year or more. As far as I know it was running fine when parked. Car sat unused for a year or more before I was asked to get it running again. Put about 5 gallons of fresh fuel in a nearly empty tank with Techron fuel cleaner. Changed the oil and filter due to dirt and fuel dilution. Initially had alot of white smoke, but this has cleared up. Now exhaust is normal if slightly rich at idle, sooty when goosing the throttle.

Car starts fine when cold, idles reasonably well until the operating temp nears 80*C at which point the idle will drop to 500 rpm or so and the car will eventually stall and not restart. Haven't had the opportunity to wait around to see how long it has to cool before restarting, but always restarts the next day or whatever.

New spark plugs (Champion Copper Plus, the old Bosch Super had same symptoms) which show minor carbon fouling, fairly new wires.

New oxygen sensor.

Distributor cap looks like new. Cap, rotor and coil all replaced at just over 300,000 miles, prior to the fuel distributor.

CPS reading was around 800 ohms cold and 880 ohms after stalling if I remember correctly.

Temp sensor readings seemed to follow the table fairly well going by the guage on the dash up to 80*C and readings were within about 0.020 ohms of one another but not identical.

OVP seems ok ... no blown fuse, no abs or eng lights other than low windshield cleaner for obvious reasons.

Fuel pump seems to be operating correctly.

Unplugged the cold start injector after last startup, same result. Runs fine until warm.

All vacuum lines and hoses look to be in real good shape.

Transmission modulator not leaking, no fluid in line.

Suggestions as to what to try next?