Yes I have the original petrol tank and a spare wheel well lpg tank. I guess he may have programmed the lpg to fuel the engine based on throttle positions and not using the maf?! I'm really not sure, I'm just so lost on how it can run perfect on lpg but not petrol.
The backfires and misfires are really bad on a cold morning start but get better when fully warm and turn into a massive burbling flat spot on petrol. It take about 15 mins to get 100 yards down the road when it's freezing out side in the morning, can't get over 10mph until it warms up.