I have a 2002 Avalanche 121,000 miles, service engine soon light is on, it has a constant sputter not a miss while driving, idles fine does not stall. The sending unit was leaking changed it and also plugs. It still runs decent but not getting full power. Air or fuel?

Have they given you the code for the service light?

At 150000 miles the plugs start to fail under hard acceleration the higher compression blows out the spark before it ignites the fuel. Random cylinder misfire causes the check engine light to come on. change the plugs!

If you know the plugs are fine then an ignition wire or a coil will cause the same symptom . If you had a code reader it would show you which cylinder is causing the miss. Beyond that a compresion test is needed.

If he said it was the throttle idle air control, that is correct. The car may not idle but is safe to drive.

The PO 316 is still misfires om first 1000 revolutions
so the shop did a poor job for you on resolveing the
cylinder misfires

Try a diffferent shop

Have to clean the MAF Sensor & replace upstream
oxygen sensors if over 100,000 miles

Need the correct oem spark spark plugs/any brand

No reason the gas filter should be clogged unless it was in
the car for 10 years

Fuel pressure should be checked

Need to check for cylinder misfires on a road test of 20
miles or more with professional software in Mode#06

Fuel Pump or fuel filter will be my first guest. Did you pull any Codes from the truck already?

Tony

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/tony_a41fa0b801734e2f

I have a 1989 chevy 305 and cannot get the timeing right. what wire do I unhook to set timeing?

go to autozone for a free computer scan and get the fault code. Possibly one of the COPS, Coil on Plug. COde will tell you

Problem solved by the dealers service department. Thanks

change spark plugs