hi Rhopac
well there is the PMTD
that is the only other component that is associated with all the other components in the circuit.
being that the truck is pulsating or surging when accelerated at the point or after the 1A switch is made tells me either the reverse circuit has an issue in the main fwd/rev contactors or the PMTD.

Since you replaced the 1A driver that rules that out, but actually if it goes into 1A in forward that ruled that out already.

i would pay attention to the PMTD and the fwd/rev contactors and coils.
If you want some basic EV1 troubleshooting help you can go to:
h t t p://w w w.fsip.biz/Documents/EV1.pdf
^^^ remove the spaces i added so this url would post ^^^

There are troubleshooting charts and diagrams that should help alot. Check tables 1H symptoms and Table 3, they cover these type issues with 1A problems.