[Jon E 85.5 944]

Thanks everyone for the posts.

After some research, and some reading on the "Clarks Garage" site (great site), I determined my problem might be the throttle position switch. I was having a hard time believing DME relay, because the problem seemed too much RPM related. I checked the relay anyway, took it apart, inspected for cracked solder joints, seemed fine.

Today, I removed the throttle body and throttle position switch, and found the switch full of moisture. After blowing it out, swabbing it out with about 20 Q-tips, and blowing a hair dryer into it for about 20 minutes, I did the Ohm-meter tests, re-installed on the throttle body, re-installed the throttle body, and wow, the car runs great. Its idling below 1000 RPM, acceleration is strong and smooth. Hope that was the problem.

As I mentioned, I live in central Wisconsin, and the 944 is my daily drive. It's parked outside in sub-zero weather often, and I'm guessing the moisture in the switch would freeze, and then as the switch would thaw, the moisture would cause internal shorting and send incorrect signals to the DME unit. We'll see how long this lasts - maybe I won't have to purchase that $80 switch after all!