I have seen this happen also. Usually its a fuel delivery problem due to clogged final chance screen located underneath lpg pressure sensor or clogged filter in lockoff. As MEngr instructed check other sensor reading with either pda, laptop or hand scanner. If lpg pressure remains in range, check final chance filter located benath sensor. If clogged, clean but take care to not contaminate injector holder by letting debris get beyond screen. Screen is held by small clip. Do not damage screen. If pressure falls out then check fuel filter in lpg lockoff. If clean you may have vaporizor going south or the lpg lockoff is dropping out and test should be performed to verify. Remember ALWAYS drain regulator/vaporizor as recommended..