1998 Dodge Ram overheating issues Options

[AWD DSM 1]

Recently got a 1998 Dodge Ram Quad Cab 4X4 with a 5.2l. Truck Ran fine for the last 2 months. Just this week, starting when the hot weather hit, the truck started missing, and by the middle of the week it was overheating. Threw a CEL, had it pulled at Autozone, it was a random misfire code. Parts slinger suggested I got some bad gas. Replaced plugs, wires, thermostat, and put a K&N air filter in. Seemed to fix most of the missing issues, but the truck is still overheating when I'm not cruising at 55mph. I read somewhere that if the alternator isn't charging correctly, it may cause a miss as the dodges are tempermental with their voltage. I checked the voltage on the battery while the truck was running and it's only at 13.3v. I'm guessing the alternator's getting ready to take a crap. My question is could this be related to my overheating problem? Could the low voltage be causing the truck to run lean/rich and overheat? Supposed to take the truck to Chicago Saturday, I would really like to get this figured out asap...

Posted also on CID, but I think they're too busy bashing each other to actually answer a technical post. Thanks for any help.