I am new to pcm tuning, i took a 350 Turbo 350 chevy out of my 1961 GMC installed a 2004 5.3 LS with the turbo 350 ran good but i have 3:73 rear gear so i needed overdrive . I had a local Trans shop build and install 4l60e (1997 4l60e) now trans shop connects their scanner and it said truck was going 158 m p h and the drive by wire throttle body stops working and trans is stuck in 4th gear but truck only going about 15 mph . I have built a test to read pcm with obdlink and have a spare pcm from junkyard but i will probably need to get a different one due to what i have now is 12597120 os out of 2007 gmc 1500 pickup and i need xfd file. Thanks for any help .

Thanks
CrankFrank