03 1500 transmission problems help please!

03 1500 with 5.7 hemi. 545re automatic transmission. Have had problems since I bought the truck. Dealership put 3 new valve bodys in it, warranty is up now. About a month ago it starting seem like it was slipping into 2nd and overdrive. But now I lost 2nd and overdrive unless it is cold but 5 miles down the roadlose them gears cause my truck slips and stays at 3000 rpm. Check engine light is on. Is it the computer torque converter tranny any ideas. If need new tranny rebuild or get a new one I just don't wanna have an problems like this. But the tranny has 150000 miles on it. I pull a lot witth the truck and use it as a daily driver.