This fuel injected propane gm 4 cyl.. engine lift has been a difficult problem for me, with my limited skills with computer and electronic sensors. The throttle body was very very dirty in the butterfly area. took apart and cleaned and then proceeded to clean with electronic cleaner the variable speed section and stepper motor. reinstalled runs much better however when putting the gas pedal down past half way it quits. starts right back up. If I ease the pedal down it seems to last longer but not always then stalls. many new parts rebuilt cyl head new timing belt and water pump and tensioner etc. plugs wires etc. Any ideas