rough idle

I have a 2001 cavalier Z24 2.4L which idles rough. I took it to the dealer they put it on a scanner and in the first 10secs it misfired on number 2cyl. so they put an injection cleaner in it because the scanner showed the injectors were acting wierd. wouldn't the injector act weird for spray it the engine was up to 700 rpms to 525 rpms. I have a k@n filter it in I was reading some other forums saying to much oil might make it to the the MAF and get the idle problem? or spark plug,wires or IAC giving me the problems? The car has 26000kms on it.