Marty:

I don't think your idea is a long shot at all.

After digging thru the archives, I've placed the O2 sensor high on the list, along with the fuel pump.

The fuel pump may also be tested easily. On my model you would pull the MAS controller that houses the fuel pump relay(and other circuits); then jumper port 1 & 2. If the pumps run and the car starts, the fuel pump relay is bad. If the pump does not run, then the pump is bad. Had to replace the MAS last year -> fuel pump relay was bad. I need to make a jumper wire to carry in the car for the next time. Sure hope that $500.00 FPR is OK.

Thanks for the O2 how-to. I'll pull my passenger side carpet tonight and get a jump on where it's at for the next time.

I suppose the snake oil could be clogging the injectors, but I'm not sure how a 1 hr. rest would "unclog" them.

The ign. coil would remain a suspect, but the surging idle would be more fuel/air related than ignition. I came across a post by psfred that associated a failing fuel pump with a surging idle. Investigation on the WEB showed heat being a factor in fuel pump failure and in both of the situations I've experienced, the ambient temp was much higher than it had been.

Summer's coming - definitely need to get this one resolved.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"