I have a 2015 Linde H30T with a 2.0L VW propane motor, with about 5,200hrs. It sputters on acceleration. If you are giving it light gas pedal it runs fine, if you mash the gas pedal it runs fine (maybe a little slow to accelerate). But say you give it 1/2 throttle it spits and sputters. But when using the electric mast controls it revs up fine also.

So the things I've done. Replaced the spark plugs and cleaned the throttle body, no change. I replaced the throttle position sensor, no change, I replaced fuel filter and vaporizer, no change.

The whole time it has never given a check engine light. So I'm hoping someone here can help before I take it into the dealership and let them fix it. We have 6 of these and this one has the lowest hours and none of the others have this issue.
Thanks for any help
Dean