My daughters Monte Carlo 1.2tsi CBZB has developed a misfire/hesitation underload between 1600-1800 rpm. I would say it's normally in 3rd and 4th, but once past that rpm it flies with no other misfires or hesitation. No warning lights have appeared on the dash. The previous owner has changed the coil pack, and today I replaced the plug leads. Before replacing the leads I plugged in code reader and it showed up that cyl 3 and cyl 4 had been logged. After replacing the leads I took it for a spin and the misfire was still there, plugged in code reader and it only showed up that a cyl 3 had a misfire. As I haven't replaced the plugs and am not sure when they were last changed that's the next job. I'm hoping someone would be able to shed some light on the issue, if the plugs don't sure the problem what else could be the cause? I've read about the turbo actuators playing up but I'm not sure that would be the cause Also which brans spark plugs would you guys suggest fitting? And if you could supply part numbers that would be awesome