Just my .02 again. Your symptoms agree with mine except my cel came on while driving. Others have had the same symptom and the consencous is to change the module. So if you take Nick up on his offer you will be out $20 shipping round trip. I would apply that $20 towards a new module. Worst thing that can happen is the new module won't fix it and you will have a spare module (and be out $120). I carry a spare of most every sensor in the trunk along with a coil pack/module assembly and an ecu. I also carry the tools needed to change them. Better safe than sorry, right? My last word of advice is to buy ac delco when possible. Usually Rock Auto has best prices, and sometimes the local parts store matches them in price. Good luck and let us know the outcome.