Hey guys,

I have a 2002 Dodge 3500 4WD Dually. With the onset of summer (100+ temps) I've noticed the temperature guage while around 70 MPH is creeping upwards of 210-215 while towing a 6'x10' enclosed trailer and having the A/C on. The motor is running at about 2200 rpm. See the photo enclosed of the trailer.

I have a six-speed standard transmission. It has the FASS lift pump. While driving at 70 my fuel pressure is between 18 and 20 PSI. It seems to lose power at 70 MPH and it will not accelerate much beyond that. Normally (non-towing), I can easily drive 80 MPH, which is the fastest I have driven it (normally drive it at 65-70 MPH).

Is this an acceptable temperature for my motor to be running at or is it possibly an indication that something is wrong? It seems to fall flat on its face under these circumstances. Any help would be deeply appreciated.