SUCCESS!!! Wanted to post this to close the loop and report success. Yesterday I rechecked the codes after it failed again and the "RPM sensor intermittent failure" code was saved. I cleared it and today I bought a new RPM sensor and also a new set of plugs. Installed the new sensor and......

Thanks for the input Lee, seeing as I did get the RPM code one time I'll order the RPM sensor and try that. Appreciate the responses on a holiday.
Thom.

Thanks to MIJ and Sweet Wagon for the quick reply and suggestions. The fuel suggestion is interesting- the car had been sitting for several months before this problem showed up. One of the first things I did when this problem started was I put a fuel treatment/dry gas into the tank and added fresh g...

I have a 94 Volvo 850 with about 98K miles on it. My problem is that it starts fine when it is cold and idles very smooth, then (at idle in my driveway) as the engine temp comes up to normal (about midrange on the temp gauge) it starts to run a bit rough and if you give it any gas it stutters, gulps...