Glad you came out from the woodwork to ask a question!
I commonly do what you do with my autobox - changing down the gears on the stick ready for instant acceleration, and for fast cornering (although a high engine speed can = less stable car). I have heard these cars can be driven 'on the stick' forever with no problems (and I have done for a year or so).
Sorry to bear possible bad news, but this is the exact symptom I had when my autobox went bad 15 months ago. It never happened because of being under full acceleration, usually while simply cruising along, the drive would be lost in 3rd and 4th gears (can't remember which one at first, but after a while, both) and I could freely rev the engine despite being in '3' or 'D'. The gearbox at this point will actually be trying to engine 2nd gear.
The only solution I found was to slow to a speed applicable for 2nd gear, and bring the engine revs up to the required revs for that speed, then 2nd would engage fine. It would later change up to 3rd or 4th gear as usual, only to do it all over again a few seconds later.
Eventually it was found to be water in the transmission oil (radiator broke) and of course, big UK £££ or in fact Can $$$ for you and a reconditioned autobox.
BUT! This is a worse case scenario. There may be a more simple fix, but generally the cheap & simple fixes in MB automatics seem to be reserved for harsh shifting/not shifting etc. not 'loss of drive while in gear'
Recommend, if the problem persists, taking it to an automatics specialist with as much Mercedes experience as possible, or a good independant garage. The dealers may be a bit too keen to assume & say 'yeah it must be broken - you need a new one. Please sign us a blank cheque'
Otherwise, keep on driving it. The engines are very solid and can stand running on the limiter. I believe 'Sisco' who sometimes lurks here, drove his 170,000++ miles 4-cylinder 190E on the rev limiter for a whole 15 minute drive to try and break the engine (he failed, it continued to run like clockwork) before removing it to fit a 2.4 supercharged beast.
hope you get good news!
P.S. There's not too many idiot lights on a '87 190E, only low engine oil, alternator, ABS, water level that's about it. Certainly no warnings about gearbox or engine problems.
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black
Last edited by pentoman; 08-14-2002 at 07:43 PM.