Guys
I had the same problem with my 2001 Silverado 5.3. In California. What a pain...
After spending days and north of $100 at the shop running monitor checks and idle tests (to no avail), here's how I fixed it myself:
1. Disconnect the battery.
2. Change the plugs, wires, clean the Mass Air Flow Sensor, and clean or replace the air filter (everything in front of the injectors).
3. Add a bottle of Lucas Injector Cleaner to the tank.
4. Reconnect the battery.
5. Run the silly drive cycle a couple times with the tank about 1/2 full.
6. Then drive another 50-80 miles for good measure.
7. Say three Hail Mary's.
8. Check the scanner for a reading like "Test Complete"
I don't know which of these steps did the trick, but one of them worked!
ps - if your plugs are frozen stuck, use a product called Aero-Kroil. NAPA sells it behind the counter in Cali. It's like Liquid Wrench on crack.
