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?

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.