I have a 2003 silverado with the 4.8l gas engine. A couple of weeks ago the check engine light came on so i used a code reader and it was saying the truck was running too lean. I assumed it was bad gas, once i ran it out though, the problem continued. Now i have read it again and its saying there is a problem with the mass airflow sensor performance, running too lean on bank 1 and 2, and multiple random cylinder misfires. The only syptoms i have noticed is erratic idle. It will go down to 200 or so then back up to 6. So far i have replaced plugs, wires, fuel filter, and mass airflow sensor. Any help with what the problem is would be much appreciated.