Solution to pickup problem: Goto any mechanic and ask him to check spark plugs of your car and clean it. The pickup problem will be solved.
Solution to knocking or missing problem(on petrol after cng installation):
Simply reset your ecu and the problem will be gone. checkout following link to see the procedure of resetting an ecu:
read zolojazz's post over there.
I got Landirenzo(italian) cng kit installed with tomesto advancer/emulator with 50litre italian cylinder for 32,500rs, different mechanics charge different prices. In my opinion the cng kit should not cost you more than 40k.