2007 5.7 Hemi in 73 Plymouth Duster (pedal cuts out)


I recently put a 2007 Chrysler Aspen 5.7 Hemi in my 73 Plymouth Duster, with a Durango 545 RFE transmission (4x4 but running it as RWD only), 8 3/4 rear end. It has the Digital instrument cluster outta the Aspen, and a fly by wire pedal.
Ive had an issue for months that I cant seem to solve.
When Im holding constant acceleration at higher speeds my accelerator pedal cuts off, and I can no longer accelerate (total loss of pedal). Its also not giving me a speed reading. The only way to get it working again is by turning car off, then back on. If Im driving the car and only gas it for a few seconds at a time I can normally avoid this issue (no constant acceleration).

*I have tried 2 new accelerator pedals, changed transmission speed sensor, and made a whole new wire harness. I still have the issue.

I was told that this issue could be caused by the fact I dont have the ABS hooked up in the vehicle. That I also need the speed sensors off the ABS system.

Has anyone had this issue? Or might know whats going on? Thank you!