1995 K1500 5.7L 4L60E limp mode

I have a 1995 K1500 5.7L 4L60E in limp mode most of the time. Codes 66,67,81,82 I have installed a new ignition switch. I have 12v down at the trans connector for the Trans harness. I have replaced both solenoids in the trans and replaced the trans internal harness. I have also replace the PCM. When this does shift it is perfect! I have checked the ground wire at the PCM and I no resistance from PCM (red harness B4) to ground. What am I missing? Is it possible that a faulty neutral switch can has this issue? I wouldn’t think it would store those codes. I have an obvious electrical fault and not an internal fault. My son has cancer and I cant afford to take it somewhere. Any advice would be greatly appreciated.