2003 silverado stuttering at idle

[Taco2131]

It could but it could be many other things. What codes did it throw?

It didn't throw any codes at all, just ran up to the parts store n it says there were no codes stored on my computer. It's been running fine today. I wondered if maybe some crud from the old fuel filter was still in the lines when I changed it n last night I got some Heet n put that in along with filling it up.

[02suburbanZ71]

Thats odd

[Colossus]

may have plugged up the new filter too...

[Taco2131]

may have plugged up the new filter too...

That's what I thought too. This thing is back n forth on me. Was driving it a couple hours ago after leaving the parts store n check engine light came on so I ran to another one n put the scanner on it. P0420 catalyst system efficiency below threshold (bank1). any ideas??

[Colossus]

not with that kind of code, no... I'd want to check upstream of the cat...

[Colossus]

Here is what I am going to suggest you do next... and this is just a suggestion. When you are low on fuel, dump a bottle or two of the Techron or BG44K into the fuel tank, fill up with 87 or 89 Octane from a good station such as Shell, Chevron, Connoco, Phillips 66.. and run that tank thru and see if you notice any difference. Need to get some good gas in there. Fuel is the easiest to eliminate. After that, if you are still getting that same code about the cat bank1 you may want to take it to a good repair facility that has all the scanners and sensors and gas/exhaust analizers that can find out for sure if you have a cat condition or if it is something upstream of that.