Lhis problem sort of started wih previous question on dodge ram fuel pump--before dropping the tank on pickup to change fuel pump, we siphoned the gas out of truck & put into camry. Gas cans used appeared clean, but who knows--hey were not my cans, but belonged to person helping with tank. Couple days later wife stated car running rough. Borrowed a "code tester" and plugged it in and got a message '#3 CYLINDER MISFIRE". Since it's been awhile since a tuneup, I guessed sparkplugs, which were replaced [iridium] but to no avail--still runs rough and check engine light on--code still says #3 misfire. Would bad/dirty fuel cause just 1 cyl to misfire? What to check next?