When you find a fault and fixing it makes the problem worse

VeccyC turned up today with running probs on lpg.....ie will run for a bit on lpg then switches to petrol.
Emissions light is on all the time too.
So off to my local friendly garage who has a 'snap on' scanner that can read CAN bus to read the codes
It had a few various ones stored including P0100 Maf sensor.
Cleared the codes and started her up......rev'd it bit on petrol.....checked the codes and nothing stored.
Switched to lpg and again rev it again....when the revs dropped it stalled after a missing for a bit.
Checked the codes and P0100 maf sensor has come back.
So I decide to check for an air leak....pop the bonnet and if you listened carefully you could hear a slight hiss.....anyway I found the leaky pipe.....it was a vac pipe connecting to a soleniod for the lpg system....and the same pipe also goes to the evapourator for the lpg......so I thought id cracked it....leaking vac no wonder its having problems. The pipe had been resting on the steering rack and you could see where it had worn through.
So I cut out about an inch of damaged pipe and joined them back together with a straight thro' pipe connector.
Now it wont run on lpg at all

As soon as it tries to switch it coughs and its back to petrol again

The engine ecu isnt storing any codes anymore......so that leaky vac line seems to have been causing the maf sensor error also emissions light isnt on anymore.
So at this point I given up with up and its booked into vx dealer in Bath on thursday.......im hoping that the pressures for the lpg are now miles out and it will just need adjusting.
Tho on the upside.....the vx dealer isnt going to tell me the maf sensor is fubared and needs changing

Oh and I discovered summat else that might interest TB and his tractor.
I was playing with the scanner in live data mode.....the temp guage was sat at 90C midway point for it.....ecu water temp was saying 95C......so the ecu seems to read 5C higher than the guage like it does on his tractor.