Hmm... in my case, when the problem's there, it behaves the same with AC on or off. Wierd thing is, that sometimes the problem subsides, or disappears altogether. I've tried to narrow down the factors which result in the behaviour, such as time of day / external temperature / engine temperature, but doesn't seem to be related to anything in particular. The only constant is that it happens with CNG, never on Petrol, and I think it happens more when CNG pressure in the tank is low.
It might as well be the coils. I had a weak coil and the car was missing stokes and making small patakhas (happened right after my driver got the inside of the engine washed), so I changed it with a Kabuli coil the only time I put a kabuli part in this car. I know it was a bad move, should've put in a new coil, but it seemed like a good idea at the time.
Anyway, it doesn't miss strokes now and no patakhas, but it still might be weaker than a new coil. There's no way to tell except ruling out all the other options. I'll get it's tappets adjusted and throttle body cleaned. If the problem persists, I'll get new coils.