My CX-7 recently started hesitating in acceleration and engine light came on. It threw a P0302 code which I've confirmed to be misfiring at cylinder#2 using a scanner. Swapped spark plug to cylinder#3 and test drove, but still hesitant during acceleration and code still read P0302. Then, swapped the coil (with boot) to cylinder#3, but still hesitating and read P0302. Lastly, replaced the boot at cylinder#3 without any change (original boot upon inspection looked fine). I cleared the error code also in an attempt to have the ECU register a different code, but all it did was clear the engine light.

I'm wondering if none of this appears to be ignition (coil and boot) related then could this be caused by a faulty fuel injector? Not that this might have any bearing on this issue, but this problem happened after pumping premium gas when the tank was almost empty. Suspect "bad" fuel, but if so, why would this only register at one cylinder?

The car has close to 100K miles and I plan to replace all 4 spark plugs with the laser Iridium type (NGK) for starters. Also, how soon does the ECU cycle between code readings?

Thanks,
JRN