Over the weekend I did my first real highway trip. I've had the truck in twice before for tranny shifting issues and they replaced the PCM (twice) and the TCM once.

It seemed the same shifting issues started to show themselves again, but I wanted to see how it did on the highway. It wasn't bad until I turned the A/C on. Any slight up hill grade caused the truck to down shift into 4th and at times when it shifted I thought the tranny was going to drop out onto the highway. Even on straight and level sections of the highway it felt like it was downshifting or the A/C compressor was kicking in so hard if felt like it was downshifting. Gas mileage was crap averaging around 16.5 with the A/C on. Hell I get that around town.

Going into the shop again, and I'm going to inquire about returning the truck if the issue isn't fixed this time.

 

dont know about the trans issue but when my a/c cycles on it hits very hard as well