Yes, I had a very similar problem with my 85' 190E. It is both your fuel pump and your relay. The pump is shorting out your relay. I went through several relays before we found this out. When your relay goes it either stalls after starting or starts hard. The relay has two settings for cold start and normal running. The cold start is working to start the car but then it switches to normal running and stalls. I restarted the car so many times before I realized what was wrong that I snapped the ignition switch which locked in the start position and ruined the starter and the fly wheel. $1800 later it was still stalling. Then we replaced the fuel pump and relay and never had a problem again. The relay also controls your cruise control because that worked again after we replaced it. Good luck! -Lj