I have a 2002 F350 SD crew cab 4X4 with approx 210,000 miles on it and it is overheating when I pull my 5th wheel or my boat. I'm running 285 tires with 3:73 gears and the truck is all stock except for a K&N air filter. The boats weighs in about 4K and the 5th wheel weighs in about 13,000K...