Here's the 411 y0: I've been having a problem lately with what I think is my car overheating. My reasoning behind this is....When I'm driving during the day and it's warm out (60-70 degrees), and I've been driving for awhile (more than 30 minutes), I start misfiring on one or more cylinders (the car lurches and burps out the exhaust) and I eventually get both O2 sensor CEL's (1 and 41). If I turn the heater on for awhile, then restart the car, the CEL goes away. This problem doesn't happen when the weather is cooler (50 degrees or below). Here are the facts: recent oil change, recent spark plug change, recent radiator replacement (from an accident I got in), both cooling fans are on all the time (don't ask why, long story), recent O2 sensor replacement, and I've got a mis-adjusted valve somewhere that's causing some clicking My thoughts: It seems like my spark plugs are getting too hot and misfiring. Is this a valid concern? Or maybe the fools who replaced my radiator filled me up with too much antifreeze and not enough water? I'm at a loss. Any thoughts or advice would be appreciated.