My 04 L5 Colorado is showing a misfire code. on 2004 Chevrolet Colorado

Chevy replaced the head under warranty around 35k miles for cylinder 5 misfire. Truck now has 142k & getting misfire code. Don't know which cylinder yet.
Coilpacks still original, replaced the plugs around 128k.
Any advice?

1 answer 3 comments
What is the code number? Anyting other than random misfire code PO300, the last number in the code is the misfiring cylinder. Example: code PO 305 is a misfire in cyl 5, code PO 302 is a misfire in cyl 2 etc.! MOST LIKELY SUSPECT: a coil is breaking down, suggest replacing ALL coils and plugs! Also suggest using ACDelco parts, if you plan on keeping the truck! However @ 142k whatever.
Why AC Delco parts. From what I see, they're around $75-$80 a piece. I can get others for as low as $24 each. What's the difference? What type plugs?
What ever you want to do, it's your vehicle and your money! ACDelco parts is what i suggested, that included spark plugs, at least use their OEM plugs. You get what you pay for.
Thanks. Just wondering why the Brand Specific recommendation. I'll be happy as long as I don't have to replace the head.