Hey all,
I have 2 8FGCU25's with the 4Y-E running LP at my plant and I'm having issues with both of them. One is (i think) a 2014, the other is a 2018 or 19.

the '18 (serial# 95385) started giving us problems about 2 weeks ago. It's showing an E06-3 (Throttle motor power supply circuit open abnormality) code and is currently running in "limp mode."
all functions (fwd, rev, lift, tilt, rotate) work, but only at an idle. If you step on the accelerator, nothing happens. Occasionally you'll get a slight fluctuation in RPM, but not always.
Being that we have 2 of the same lifts, I swapped out the pedal, throttle body, MAF sensor, and ECM. None of which made the code go away (even after having the battery disconnected).
We had 2 different forklift techs (one being Toyotalift) look at it and neither were able to figure it out. Toyota tech hooked his laptop up but was unable to read it, which is a big red flag to me.
I traced wires between the ECM, pedal, and throttle body testing voltage and resistance and I used the other truck, which does run, to compare the results. everything matched.
I'm at a loss as to what to check next...

Now, the other lift....

The 2014 (serial# 45339) runs, but doesn't always run well. Last week (Friday) the guys were having a hard time keeping it running. After stepping on the accelerator, it would spit and sputter. sometimes it would eventually rev up, other times it would backfire and die. wouldn't always start right back up either. Saturday morning I had to come in so I tried running it and had no issue.
It almost seems like it runs worse after it's been at operating temp for a while. I came in today and its running decently enough without constant stalling.
I checked the plugs, wires, cap, rotor, throttle body, intake system and found no issues. I adjusted the air/fuel mix screw on top of the vaporizer a bit and got it to run slightly better but not as good as I'd like. Help, please?