I could really use help from you experts on a problem with my 124. The car normally runs beautifully under all conditions; idles fine, accelerates without hesitation or stumbling, pulls strong, shifts cleanly, runs all day long at 80 mph. Cranks a bit longer sometimes on cold starts, but that's about the only weakness. 194K miles on the clock.

Now the problem: last weekend made a 6-hour high-speed trip on Interstates, cruising for several hours at a time at sustained 75-80 mph. Pulled off for gas, and as soon as I'm on surface streets at low speed, particularly stopped for traffic signals, the engine idles very rough (RPMs go below 500), to the point that I have to keep light pressure on accelerator to keep it running, and it stumbles badly trying to accelerate from a stop. Accelerating, car is very sluggish, totally under-powered. Shut the engine off, even just long enough to fuel-up, and starts and runs fine again in every respect. Run along at 75 mph for a few more hours, slow down in town and the rough idle/sluggish acceleration returns. All it seems to take to get rid of the problem is to turn the engine off for even just a few minutes. Problem never exists if I just drive around town, only after prolonged high-speed driving.

Recent (within 2,500 miles) maintenance/service performed: new OVP, new battery, all new filters, all fresh fluids, new correct NGK non-resistor plugs. Routine maintenance always performed. No obvious evidence of vacuum leaks ("economy" gauge usually pegged left at idle, except with A/C running, when it rides about quarter way). No CEL. What do you make of this situation? Thanks guys.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't