I bought my 89 300E, which now has about 180K, a year and a half ago. When I bought it, it had a slight miss at idle and it ALWAYS took at least two tries to start. I replaced the distributor cap, rotor, spark plugs and wires, air cleaner, etc. to no avail. I have put up with the miss and hard starts since then. After reading this post yesterday, I took out the OVP, checked the fuse (which looked ok), and put it back in. When I started the engine, it choked, girgled, spit and basically ran as rough as it ever had, and oh yeah, the ABS light came on. I removed the OVP again and sure enough, the fuse was blown. I replaced it, reinstalled the OVP and walla, the car is now running like a sewing machine (not bad for 180k miles). BTW, with the OVP out, when I shook it a little, it rattled. I'm guessing this is not a good sign (I ordered another one this morning anyway). Has anybody else experienced a rattling OVP? I totally agree with one guy in another thread who recommended that we be more diligent in posting the results of our work. I have read many threads which have numerous replies that just end with no solution (even if the solution is...I tried it and it didn't work...) At any rate, the solution to my problem was....hard start + rough idle + ABS light = OVP.
Thanks for all who contributed to this thread.