LPG kit problem, after every 10000Km,starts giving jurks and miss fires, have to replace Gas filter

Car Economy was better when LPG was 23.5 Rs./Lt now rate is 30 Rs/Lt, Diesel Economy is better,Reqires to Replace Gas Filter every 10000 Km,else vehicle starts giving jurks and miss fires, which costs Rs.175/- + Labour. On Highway Santro is better than WagonR for Blancing and while taking sharp Curves and 70 Km/HrFuel economy is equivalent to Diesel,now LPG is 30 Rs./Lt, LPG has less pickup than PetrolNot good for Highway, cannot take turn at 70 Km/Hr. feels has if its going to overturn.Santro better