I need help, I have a 94 GMC 1500. I put a 5.3 and a 4L60E transmission in it. For some reason the transmission seems to be in limp mode starting off in second gear. originally I thought well maybe the transmission I had rebuilt was bad so I took another transmission to a totally different shop and had it rebuilt same thing. Found out that I had a wiring harness off of 6.0 and 4l80 transmission so I replaced it a 5.3 4l60 wire harness, SAME ISSUES. After that didn't work I thought well maybe it's the computer so I got another computer, had it flashed and still the same issues, next I found out that the pink and white wire on the blue plug (C1) terminal 38 was not in the wire harness, so I added it to the harness. I ran into an ignition wire still same issue. My engine came out of a 2000 Chevrolet Tahoe transmission was built for 03 (let me add this is the second motor I put in it also, because the first motor was knocking which was the 2003). ECM 2000 Tahoe, wiring harness 2000 Yukon, 2000 53l, 2003 4l60e. WHAT AM I DOING WRONG. I am not getting any codes, also had Joey Little (JL Remote tuning) to look at my tune and make some adjustments, but that didn't work either😫😫😫😫😫😫😫😫😫😫.