I just bought a 1986 E300 with inline 6 the car runs good when its cold but when it warms up it acts like it may be flooding out it will run as long as you keep it at about 3 to 4 grand on the tack but thats not gonna work it runs really smooth while its cold but the warmer it gets the worse it runs itll run for about 15 to 30 minutes and then it quits starts back up a couple of times and then no more untill its completely cooled down I think thats because its flooded butI could be wrong thought it might be the fuel pump but it seems to working fine comes on builds pressure and shuts down like its supposed to would really appreaciate any help with this not a mercedes mechanic at all but do like the car alot

 

i dunno buddy, sounds like the catalytic converter to me.

 

change the coolant temp sensor... $35 ....even if that's not it it wouldn't hurt to replace it anyway. the coolant temp sensor is the most important sensor on the engine...everything is fed from this sensor.....i'd start there, it's the cheapest and easiest place to begin....good luck

 

My Car did something similar to this... couldn't figure it out. No codes etc.... then I got out and listened to it run.. Fuel pump was "grinding" and not providing enough fuel. Replaced it, no problems now.
Just my .02,
Rob