I have a 2005 Chevy 1500 Silverado, 5.3 Flex. 20,000 miles.About two months ago, my check engine light came on. Went to the parts store and found out it was the mass air sensor, and changed it out with exact OEM part. The truck still struggles going uphill, trans seems to be shifting properly. Could it be another sensor, gas filter, etc? It just seems the engine is struggling. I have always used pure gasoline, not flex fuel.

whatever caused the MAF to stop responding (these have rare earth metals, and are pricey) the first fail also was the reason for the second fail. The egr should divert air on a circuit that the MAF doesn't see....perhaps some stuck or disconnected bit of hose plumbing is causing failures. things do not seem right in denmark, for something that's so new. Must be something really small and silly!

the beloved EGR is cause for unseen badness in performance-

The check engine light is off, never came on again. I haven't disconnected the battery to reset. I was on rough rocky road a week before this started. The connector to the MAS was tight. It doesn't feel like I have a mis, no rough running. Bob, that's what I was thinking, something is disconnected. I looked but can't see anything. I'll give it another try and disconneted the battery. Any suggestions where to look, vacuum line, connector?

look for a diconnected vacuum line, this would explain everything~

look for something that isn't working right. test stuff if you can by removing to see if vacuum or pressure IS on the spot, or get one of these suction/gauge devices where you can apply suction to see if a device is doing it's job...these are quite useful- but the check engine light will reveal what needs attention. You could go at it "commando" and test everything like a madman, but it's best to have a little intelligence behind your tests- I can look to see your vacuum diagram to make an educated guess-

god forbid a choked catalytic converter...now why might this happen? Something in the computer told it to run rich, and now we've got a hot converter because some of the energy of the gasoline is firing off in your exhaust, in the Catalytic converter! gotta make it run right before replacing the cat or we'll have deja vu all over again!

No funny smell from exhaust, starts great also. I'm going to change the gas filter and take a run up to the mountains and if that fixes it.

yay!

I guess the gas filter for my truck is in the gas tank?

probably a small can with nipples at both ends. 'bout 3 1/2" lg.

I got a 2004 Silverado check engine light goes on but goes away last bout couple 30min at 350.000miles Let me know anyone !!!