Car jerking in Low RPM while driving in both CNG and petrol

My Honda City Idsi 2006 (Jazz/Fit) is jerking (loss of power) in CNG mostly in second and third gear. The car starts jerking only between 1,500 to 2,000 rpm while pressing accelerator after changing gear and releasing clutch. The jerks only starts after driving it 5 to 10 kms. My mechanic repaired all my ignition coils that were leaking current and the CNG jerking problem got resolved for few days. But after 10 days the car again started jerks in CNG. I have changed all of the ignition coils two weeks ago as I hoped that it might be ignition coil problem but the problem persists. The spark plugs were also changed but only front 4 spark plugs were changed. In petrol along with jerking the acceleration time also lags very much means as soon as I release clutch in 1st gear the accelerator does not work and the car rpm goes lower than 700 but in second attempt it starts working it does it every time mostly in lower gears only in petrol. Please help me as I have changed my car's throttle body and MAP sensor. Computerized tuning has also been done 4 days ago the air filter was also cleaned a little with pressure air. My mechanic also repaired one broken vacuum pipe that was connected to intake manifold. After every work done in my car the car initially seems to have cured up to some extent and the jerks gone but again the problem came back though not much noticeable as earlier.