Just bought forklift in this condition. Previous owner replaced regulators. Forklift starts and idles great. As soon as you start to give it throttle it sputters and "chokes" itself out. If I place my hand 1/2 way over the carb to cut off the airflow it revs up perfect! 100%. I initially thought it must have a major vacuum leak somewhere.....but I cant seem to find that. Then I thought maybe fuel supply? Then previous owner told me they measured 1psi of propane pressure....but I dont know exactly where that was measured??
Is there a fuel filter or screen somewhere that could need servicing??

Thanks for now