2001 Volvo erratic speed

I have a 20001 Volvo D12C 465/ 10 speed eaton autoshift. While driving down the road ill have the speedometer start jumping up and down and the engine starts to cut in & out intermittently every few seconds while giving it gas, if i let it idle down the road nothing happens. Had codes for Accelerator Pedal Position % and speed sensor on the transmission. I replaced the accelerator pedal and the 2 speed sensors on the transmission. The truck was fine for a few weeks, no codes or any issues. Then all those symptoms came back, but no codes were showing up. Found out i didn't have the correct EECU on the engine. I got the proper EECU and got it programmed for my truck at a VOLVO dealer. Picked the truck up from the dealer and everything was working great. I drove the truck about 350KM and the truck started acting up again. The truck started showing me codes and a "Check Cab Controller at next stop" Message.
The Codes:
Cab Controller
SAE J1708 DATA LINK
MID 144
SID 250
FMI 5

Cab Controller
Road Speed
Electrical Fault
MID 144
PID 084
FMI 5

Engine
Road Speed
Unknown Fault
MID 128
PID 084
FMI 11

Engine
Road Speed
Communication Error
MID 128
PID 084
FMI 9


I ended up changing the Cab Controller(VECU) thinking it was over heating and shorting out, because everytime i would let the truck sit for more than 8 hours it would be fine for about 20min of driving till everything came back. If anyone has any idea what this could be i would greatly appreciate any input.
Thanks

 

Would what you said give off open circuit codes? Planning on pulling the doghouse tomorrow and start searching through the cables. Maybe I'll check that wheel inside the transmission before I do anything big.