I recently did my valve covers and intake manifold. Completed replaced. I also replaced my spark plugs and coils, all 6. Double checked all connections and for air leaks. Reset the throttle body. BUTTTTT I’m still having a random/multiple cylinder misfire code pop up. I know with the Intake Manifold I have on, the Air to Fuel is off and needs a tune, but after hearing and seeing what other people have done and said it still wouldn’t run the way it does… please help. I’m not to mechanically inclined just messing around and figuring it out on my own. Just need a little guidance.

 

Double check your coil pack harness connections. People always get the cylinders mixed up, common mistake.

I think the ones that get flipped are cylinders 1 & 3 and perhaps 4 & 6 (can't remember off the top of my head). But if you do some digging you can find information on this.
Good Luck!
-Icer