Thats pretty funny, i have a misfire on cylinder 6 that i cant get rid of. The difference is that i dont feel the misfire but i have the check engine light on that tells me cylinder 6 is the problem. The only thing i noticed that is the same with your items and mine are the plugs. Might just go back to acdelco and call it a day.

As for your issue i had a similiar one with another truck of mine and even though the wires were only 4 months old they were bad. good luck and keep us posted.

 

This is my first time here so I may be doing this wrong. Hopefully some one has some ideas to help me...

I have 96 silverado 1500 5.0 4x4. I did a tune up..plugs, wires, cap, rotor, air filter... when I put everthing back together and started the truck. The CEL came on and I noticed I forgot to plug the sensor plugs for the air filter back in, when I pluged them in the light went away. After a day or two the CEL started to blink (P0301)..It has been mifiring ever since in cyl#1. Did a compression test and all was fine in that respect. I changed the fuel filter and re-replaced the cap and rotor just in case it was bad, no change. Im stumped! We did do one other thing because I have spark in all plugs we pinched the fuel return line closed about half way, when we did this the misfire went away. Any ideas would be awesome..