Not shifting? One day it works fine but most of the time it's in this low acceleration mode

I've had this issue with the truck for the past year, one day it works fine but most of the time it's in this low acceleration mode where the truck feels like its starting in 2nd or 3rd gear from a stop and its very annoying. Going up an incline also requires me to floor it when it's like this. Speedometer doesn't work (its at 0) and the same with the tachometer. The odometer and trip set don't move as well. The gear selector light is on and moves with the shifter with the key on but goes out when the truck is running for some reason. The OBD1 is throwing the codes 81, 82, and 83. I'm ultimately stuck between thinking the ECM is bad from the three codes, the speed sensor/sensors are bad or the ignition switch harness under the key is bad and I need to trace wiring. I also recently found a thick white wire broke off from being grounded to a bolt above the brake pedal, I'm not sure if its related.