I wanted to have this opportunity to say thanks to all the people who contributed to this awesome thread. It is so much informative and all the people are replying to the queries with full sincerity.
I have 99 model khyber. It has missing problem. Sometimes it runs like a charm but sometimes it missfires/backfires so hard that the whole car jerks so hard that the gear handle moves back and forth. When it miss fires it hesitates to accelerate. I am having low mileage on CNG. I think miss fire is the reason of low mileage also.
I read in another thread on pakwheels that the coil could be the problem. So I changed the coil and replace it with the cabli coil. The starting is perfect now but the main missing problem is still there.
I also changed the distributor cap because it seemed to be that it is a bit rusty but no change.
It would be very helpful if anyone can guide me in diagnose my car.
Somethings details I noticed that might give some hint:
. missing has nothing to do with car being hot or cold, it is perfectly random
. missing only happens in the initial range of rpm.