I encountered a problem with one of our FG20ST-14 trucks yesterday. Engine is the Nissan K-21.
The engine starts reluctantly and then will only run at idle RPM with the accelerator in the idle position.
When the accelerator pedal is pushed down, the engine begins to stumble and falter and most of the time the RPM will only go as high as 1,850. Most of the time the engine will stall out and die when the accelerator pedal is pushed down.

When I did the "Key on-engine not running" tests using the Hitachi service reader scanner, I get voltage levels from the 2 accelerator pedal position senors that are "text book" matches to the manual specifications throughout the full range of pedal travel.
The voltage values for the 2 throttle motor (ETC) sensors however are way off base.
Manual states ETC sensor 1 should be.6 V at idle and.7 V at 2,000 RPM. Actual readings on Hitachi are.91 V at idle and.91 V with accel pedal down (engine will not attain 2,000 RPM).
Manual states ETC sensor 2 should be 4.5 V at idle and 4.5 V at 2,000 RPM. Actual readings on Hitachi are.95 V at idle and.95 V with accel pedal down.
I get the same readings when I do the same tests with "Key on- engine off".
The MIL works and is not showing any DTCs.
The Hitachi also shows no stored codes nor any "real time DTCs".
We have not previously had an ETCA to fail.
Also, at the present time, we have no other -14 Komatsu at our location that we could swap out the ETCA with for comparative measure.
All functions of the Nikki LPG regulator are correct with output of 4.5 PSI.
I think I must be looking at a defective ETCA unit, but if anybody has a different slant on this I would like to hear it.