my nissan sunny has a 1.3litre 4 cylinder petrol engine which i have conververted to LP Gas bout 5 years ago. i normally run on lpgas the whole day and when i park aat night i convert to petrol and switch off. the next day mornin i start in petrol and convert back to gas. the car was fine all the time until now. Now there is a big miss in the engine. i checked the spark plugs, distributor cables, dalco and everything but only manage to fix the miss temporaryly. i can never get to perfection. even when my engine is on idle it regularly has this jerk. which gets on my nerves when driving. specially when driving at a low rpm. I'm wondering if it is my carburetor which need to replaced. cos my mechanic always says he just cleans my carb. then my car runs smooth for bout two months ans my problem is back again. pls help me on this.

Try by increasing your engine "idle" rpm .This will be done by your mechanic.