Alright, I have an '03 Ext. Cab Silverado with the 5.3 Vortec. Me and a buddy tuned my truck using HP Tuners and a wideband tuner. We put a tune on that was supposed to be the Hypertech Power Programmer III tune, but it had massive timing increases, so we backed them off a bit. About a week after we tuned it, I noticed my truck would chug a little when accelerating from a complete stop. Now, if my truck idles for any amount of time, the RPM's go down to almost 2000, and the engine had died before. I'm pulling a throttle position sensor code. So anyway, my question is, do you guys think the sensor is bad or it has something to do with the tuning? Any help would be greatly appreciated, I'm tired of my truck not running good.

 

I would re-flash back to your stock tune (you did store/save/upload your factory stock tune) to see if you get a SES code for the sensor.

 

did you use a downloaded tune or did you copy what was done to it.