I've had my 2009 vibe for a while, it's at 200000 miles and I changed the spark plugs on it and it ran great for about a week, then all of the sudden on my way back from a 2 hour drive, any time I got around 2000 rpm it would jerk really bad like it was having trouble changing gears but only when I would hit 2000 rpm and it got gradually worse then as I was pulling into the driveway the check engine light came on. So I called a mobile mechanic and he ran diagnostics on it and found that it was misfiring in cylinder 3 so he took them all out and cleaned them and put them back and we started driving and at 2000 rpm it would jerk a couple of times and then just lose most power, check engine light came on, and only go 10 mph with the pedal to the floor, but once he cleared the codes again it would drive fine until 2000 rpms and do it again. He thinks it may be the spark plugs that I replaced the NGK's with (auto lite). Has anyone else had problems after changing to an aftermarket plug? Any information would help, I don't think it's the transmission because it runs fine up until that point, only has a rough idle after the engine light came on.
Thanks