Well, I was facing exactly similar issue. Thanks to GOD I have a very good and educated mechanic in contact, my problem got resolved.
First of all I went to CNG mechanic, I told him jerks are very minor on potrol but great in CNG. After inspection he said one of the spark plug coil must have been damaged, go to some mech with computer to diagnose which one is faulty. This was the point when I decide to go to my main mechanic who never ever disappointed me ALHUMDULILLAH.
After inspecting and performing some tests my mech said coils are working perfectly fine and I see no problem in your car, it seems to work perfectly fine. After hearing that, I asked him to come with me for a test drive on a long clean road, he instantly agreed.
During drive, in start he did not feel minor jerks but after a while he started observing, and became serious. He stopped the car to a near by Auto Electrician shop and told him "Majeeb Bhai, I feel car is lacking current some times, I've already checked, coils are fine.". Majeeb Bhai, believed what a mech said and went to fuse box in the car's bonut. Made all the fuses and relays seat firm in their position and said check now. We took a test drive again and problem seemed to solve.
Then Majeed bhai told us that 2 fuses are getting heat up and melting. Change the whole fuse box with some Kabli. Your car is working fine for now but may get problems later. I asked him what would be the price of a Kabli one, he said 4-5K. I didn't like the price and asked him if any work-around(Jugaarh) is possible? he said yes we can by pass the 2 fuses who are heating up and melting. I agreed to do this and Now MASHALLAH, I'm satisfied with the car performance.