Towing rated for 5,000 lbs. Pulling a 3,800 GVW travel trailer, empty tanks, lightly loaded. Trying to make it up I-80 out of Salt Lake City on a 94 degree day. Temp gauge hit the 3/4 to red zone. Coolant temp read 240 degrees. Engine stops pulling, limps over the crest at 8,700 feet, will go no faster than 40 mph. Same thing happened over Montgomery Pass in Nevada. Had dealer do coolant flush and fill, AT filter and fill. They did update PCM and TCM software. No problems making hills throughout the Midwest. Anyone else have this problem?