When I switch to LPG the car runs rough, the revs drop and then it stalls. The LPG light doesnt even come on either or the gauge, Its a factory fitted LPG so the fuel gauge is also the LPG gauge when switched over. It also smells slightly of gas under the hood so maybe a leak? I bought the car about 3 months ago with an empty gas tank and have only just put gas in it.
What might be causing the car to stall.
It could be that it is not tuned get the car tuned by someone that can do both gas and petrol and the gas smell could be because it it tuned to ritch causing the car to flood try this and it should work nif it dosenot he will tell you whats wrong with it its time i get mine tuned again lol only costs 150- 200 max
take it to a gas mechanic i would not touch it.
More than likely an air leak. Perhaps one of the smaller hoses has been dislodged. Try tracing all the hoses to see if they are all connected. If it is a V6 there is one under air intake on motor that can be easily dislodged. But also take it to gas mechanic if you don't find anything that solves the problem
check all your fuses as well, usually if its a vacuum leak your gauges and indicators should still work.