I have a Chrysler Sebring which was professionally converted to run on autogas. It ran fine for 25,000 miles but then started to stall, particularly when cold. It stalls now for no reason, and when you back off the throttle it just stops. It has been in and out of Chrysler dealers since the beginning of the year, but they blame the LPG and say that the car is not covered under warranty. However, as they cant find the fault, how do they know its the LPG? Is there any thing I can do or has anyone got any ideas how to fix it?