cylinder 3 and 4 misfire

I'm having an issue with my 2000 323i..when the car is idling for more than 3 mins it will start rough idling if I turn of the car and turn it back on the car will drive fine until I let It idle for more than 3 mins I ran the code it sshowing cylinder 3 and 4 misfire so I got all new spark plugs and coils and it continues to show cylinder 3 and 4