In short the problem with my 1992 300E only occurs during the first 10 or so minutes after cold starting. When I drive and get off the accelerator when approaching a stop sign or rolling down a hill, the RPM needle jumps to 0 and the engine stalls once the car slows down.
Now here is a more detailed explanation:
Again, this problem only happens after cold starting. I think this is KEY when diagnosing the problem. I've had it at several certified Mercedes Benz dealers, but none have found anything because the error simply doesn't happen when they check it out. Also because these older models don't have a hard drive (i guess), the error is not recorded and thus makes it so hard to diagnose. Here is some more info on the car:
It's a 1992 Mercedes Benz 300e. Automatic transmission, 125,000 miles. Get's serviced regularly, and otherwise is in a very good condition. Again, I get oil changed regularly and only tank premium gas (93). It runs at around 600-700 rpms when idle. I bought this car new.
Here is what happens in a more detailed descriptions (please bare with me): When cold starting (after the car has been sitting around for 5+ hours) I drive around, and i guess the cold start protection at first doesn't allow me to go very fast. Anyways, I go slow until it finally shifts up and continue driving. I go over a hill and naturally get off the accelerator to roll down. Immediately after i get off the gas pedal, the RPM needles JUMPS (that's right, JUMPS) to ZERO. However the engine doesn't stall at this point. IT STALLS when the car slows down at the base of the hill. That is, the car doesn't stall while I'm moving at a certain speed, only once it falls bellow a certain speed. Since this occurance is quite frequent, I learned to prevent the stalling of the engine, by accelerating furiously. Sometimes, if I'm lucky, the rpm needly gently moves to the regular RPM for the specific gear, and the car runs fine. If I do nothing, or I can't accelerate and I have to slow down, the ENGINE STALLS, all the lights turn on and the steering wheel is hard to turn.
When this happens I stop the car, put it back in PARK, and try to restart the engine. Sometimes it takes a few minutes, other times it starts up immediately.
Again, after this, sometimes the problem doesn't occur again, other times the same thing happens at the next stop sign. But after about 10 or so minutes, the problem is gone. Note, this also happens when the engine has reached normal operating temperature of around ~80 degrees.
While this is the main problem, I've also encountered another problem twice when I'm at a complete rest, and want to accelerate and then the engine stalls immediately. This problem is less frequent yet ALSO only happens during the first 10 minutes of cold start.
I really want to STRESS that the problems ONLY occur after a cold start. I've searched the board and seen people with similar problems, however the suggestions didn't really make sense to me, nor do I think they apply to this problem. If this ONLY occur during the first 10 min after cold start, what could be the problem?
What specifically runs during the first 10 minutes after cold starting that does NOT run otherwise? What happens that simply doesn't happen when the car has been running for a while? I've tried letting the car warm up for several minutes, yet the same problem occurs? This is simply mind boggling and I don't know what to do. Dealerships can't help me as they can't diagnose it. The car overall is in a good condition and I don't want to lose it.
I'm completely at a loss, and hopefully some of you can lead me in the right direction. I would appreciate it SO SO SO much. It's a beautiful car, and I'm scared to drive it, get stuck in traffic, and have it stall in the center lane :(.
Again, thanks in advance for your help and for reading this.