I am hoping someone can help me. I bought the truck with this problem and cant pin point the problem. The truck has po108 pending after you drive the truck on the highway for a short period of time say 10 minutes. The check engine light never comes on because it resets itself after you turn the key of and on. I guess the problem is not there on start up and you can drive it around town and never have a problem. Anyway I have check for 5 volt at plug and check resistance to ground and appears to be good. I went ahead and replaced sensor hoping that it would fix it and it didn't. Maybe vacuum? Truck has a magnacharger and gm performance intake. Truck seems to run fine but when the code is pending the trans goes into safe mode and shifts hard. Any help thanks