Chuck,

I checked the engine control unit after I drove to work this morning (about 18 miles) and it was barely warm. Checked it again after I got home this afternoon and it was quite hot. So, since I had a spare in the trunk, I decided to go ahead and replace it.

It usually only surged after being driven for a few miles, so I don't know if engine temp is a factor or not. I replaced the temp sensor (near the water pump ???) a couple years ago as well. If this is what you're referring to, then that shouldn't be the problem. However, it may bear swapping out again if this doesn't fix the problem. I drove it to a restaurant near the house for dinner, but probably not long enough to get the engine temp up...i that's the problem. I'll drive it to work again tomorrow, which should give me a feel for whether that's the problem or not.

I'd hate to try and run a vacuum leak to ground, but that will be one of the next tasks to tackle if swapping the unit didn't fix the problem.

I appreciate the tips on what to check out.

__________________
Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000