2003 gmc envoy 4.2L
It won't go over 20 mph on flat land, goes crawling up
hills, has loss of power but idles fine. We have replaced
the fan clutch, serpentine belt, and now put a new throttle
body with throttle position sensor on it along with oil
change. Any other ideas as to what it could be?
Have you checked your fuel pressure (fuel pump) and/or fuel air mixture (Mass Air Flow Sensor)? Are you getting any error codes?
Fuel pressure and flow would be my first guess also. But if that checks good then Live Data Scanning might be the way too go on this one as you didn't mention seeing a check engine light.
Forgot about exhaust system back pressure, will the engine rev up if you goose it in park? If not that could also be a problem.
The check engine light comes on, blinks a few times then stays on before blinking again and just repeats the cycle. I'm not sure if the fuel pressure & flow has been checked. They are supposed to be checking the exhaust system tomorrow.
If you go to a car parts store, you should be able to borrow or rent a code reader. If the check engine light comes on, it should store an error code that you can get with the reader. One of the major parts stores loans them for free (Autozone I think but not sure).
What was the answer??