You probably right. I bought a special cable for my type of LPG ECU. I also have a program for this instalation, so i can use my laptop and adjust whatever i want 
Thats very usefull if you know how to do it... 
I would quite like something like that for mine... I used to have a logger on my Impreza WRX STi to monitor injector duty cycles, ignition timing etc... Would be interesting to see what all the LPG system is doing. I sometimes get a stall when dipping the clutch to come to a halt after a high speed run (usual place is at a roundabout coming off the motorway) which I'm convinced is due to the fuel cut on overrun being too over-zealous due to being on a closed throttle while slowing. If the Omega's pedal layout wasn't so poor I'd be blipping the gas on downshifts, but I physically can't heel-toe in this car

. I'm sure a quick adjustment on the gas ECU would sort it. In the meantime I have modified my driving style to dip the clutch a little earlier, and if it does try to stall I just lift the clutch again while the car still has momentum to lift the revs back up -- after that it sits perfectly idle at 600 RPM.
Where did you get the cable and how much did you pay? I can probably get the software easily enough (according to some online groups it's freely available although I haven't actually checked), and the cable can be bought for around £70-80, but it's quite extortionate for what it is.