So running the car into a floor and pulling the door zone input from the mag switch doesn't recreate it? The first thing I would check is your P24 in the controller. If it's lower than 24, re-tap the transformer. You said the switches are good, does that mean you have replaced the DZ mag switch or at least swapped it with LU or LD? I recently had a 1A intermittently stalling at up level, LU switch was only passing 19 volts. I assume you would only get this fault if the DZ input was low but it would be interesting to see what happened if you pulled T11-1 at the controller, at least rule out a travel cable wire. Although it is still possible the travel cable wire is grounding out, pulling the input low.