Toyota 8FGU25 ser# 47165, dual fuel (propane/gas) forklift runns perfect on gasoline but not propane. To start lift would not idle properly adjust several times with no success. checked pressure out of regulator found low at 2.5 PSI so replaced regulator as it is only form of pressure regulation. I now have good idle but when try to bring RPM up it shakes and stummbles to the point of dying but restarts fairly easy. Any suggestions would be greatly appriciated thank you