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

I used a Speedhut GPS Speedo gauge. So I can’t help with that. Just throwing this out there, have you cleaned the throttle body. I know it will cause some crazy stuff to happen. My son just had that problem where it would go into limp mode on his 2015 Ram. I told him to clean the throttle body and it fixed his fault.