About once a season, I would have a rough-idle problem, and it usually cleared up by the time I had pulled out of the driveway. This year, it was a little different. Tell me what you guys think of the latest:

My 1992 500E had about 55,500 miles on it when we set out for the west side of Michigan for a lake weekend. Like a bonehead, I had let the car sit from Nov to March with about 1/4 tank of fuel, so I filled up before we hit the road. The tank was almost dry by the time I filled up, and I probably didn't pay enough attention as I was filling up to fill the tank slowly, not at full blast, so that I wouldn't stir up any junk that might have developed over the winter.

After filling up, I went about a mile to the DIY car wash to get the dinge off the car so it was a bit more presentable on the road (I know, I know, avoid these places, but the car looked bad and I didn't have the time to handwash).

As I pulled out onto the road, the car started hesitating and bucking like crazy, and even with the pedal to the floor it was not making full power. I figured I had stirred up some crud and plugged an injector, and once the car shifted into 3rd and hit around 40mph, it seemed to settle down. I reasoned that at higher flow rates the spray pattern from the injector was not as critical as at low speeds, and once on the highway, it seemed back to normal.

Drove the car about 400 miles altogether with no probs. Refueling after an hour on the road, the "Check Engine" light came on as soon as I fired her up. Stayed on the rest of the trip and after each subsequent start.

I took the car to the dealer where they diagnosed the code as "Lambda Integrator at Stop." According to the tech, this code had set 128 times (?!) before it turned on the light. They tested the emissions system and determined it was working within spec. They reset the light and it did not come back on, and in light (pun intended) of this, only charged me for 1.5 of the 3 hours the tech had in the job.

Later, I recalled that one of the air box clips was still off from when I installed K&Ns way back in 2001. I had them reinstall the clip, just in case. So far, with another 30 miles of driving, no sign of the light, although tomorrow I'll be putting 100 miles on her for a short biz trip.

Any ideas, guys?

Kirk
1992 500E
Pearl black/gray
55,900 miles