Sometimes when I start my 08 cobalt SS it runs a little rough during cat warm up. Only mod is a k&n typhoon intake. Sets a random misfire code along with cylinder 2 and 3 misfire codes. Does it only for like a minute then runs perfectly fine. Any ideas?

 

I guess the only suggestion I have would be to swap coils 1 and 4 with 2 and 3 to see if that changes codes to cylinder 1 and 4. Then I would say the coils are bad. How are your plugs?