This may have been covered in another thread.
Wifeys car is an AU11 Fairlane Ghia with a VCT engine.
Recently fitted LPG the car runs fairly well however when you are just coasting up the road ,say to a roundabout or corner the flame just goes out...Engine drops to well below idle and just keeps going lower than John Howards approval rating...Absolute b**ch to restart as with the Fairlane you have to go back to park and cycle the key to restart. Runs smooth as silk on petrol but only has this problem occasionally ,has the fella from the installation company scratching more than his head .
Any help greatly appreciated..

could be the breather hose from the convertor to the airbox

try removing the intake snorkle

seen it work a few times