hi everyone i just joined this sight and i need a little help. i have a 1998 mustang
gt with 90k miles on it and i just swapped the intake manifold because the stock one had a crack on the coolent runner right next to the alternator and it was spraying everywhere and the coolent would get into the spark plug holes and cause them to short out. after i swapped the manifold it is now giving me a P0303 code and thats a misfire code on cylinder 3 i have replaced the plug and the wire and it still gives me this code. now it seems to miss randomly sometimes it runs great and others it has a terrible miss is it possible that the injector is failing? i have unpluged the injector while the car is running and it didnt make any difference in in idle but could that just be because the cylinder isnt firing at all? i am a really capable machanic i do it for a living but this problem has me stumped so any help would be greatly appreciated thanks.
ps the new manifold in an oem manifold it isn't an aftermarket one