S500 Coupe Suddenly Dies, but Restarts

[ctaylor738]

About a month ago, my (so far) completely dependable 1996 140 coupe stopped running at a light about 2 minutes after starting after sitting for two hours. No warning, no stumbling, just died, leaving all the warning lights on, like the ignition had just been switched on. About ten minutes later, again at a light, it almost died, but then did a little surge and stayed running.

I sought local advice, looked at the TSB's, did a Search and replaced the crank position sensor and added a .5 mm shim as advised.

The problem went away for a couple of weeks, and then it happened again just as I was coming to a stop. More consultation, and advice to try a different key. I also had all of the codes pulled from all of the modules, and nothing relevant showed up.

OK, so with a different, barely used key, the problem did not recur for a few days. Then, a couple of nights ago, driving at 25-30 mph, I could feel the engine lose power, twice, for less than a second each time.

The only other weirdness with the car is occasional ASR/ABS lights that go out when the ignition is cycled, but this did not happen in any of the recent dieing episodes.

I am considering a fuel pump relay. The fuel pump was replaced about 18 months ago and has about 8K miles on it.

So any other suggestions on what to test or what to try? This is a rather large car that you don't want to die on you in traffic.