Who told you that if a car is continuously run on CNG its rpms are increased. Its obviously not true because here are members who have driven their vehicles 200k+ and obviously have driven atleast 150k+ on CNG which is far greater than your mileage and their cars idle at 750rpm on petrol.
I think when you first turned on the AC your car started to perform badly on CNG so you went to a roadside mechanic and increased the idle rpms by juggar and that disturbed the synchronization of TPS, MAf, MAP ets. Now what you have to do is bring back the idle rpms on petrol 800. Disconnect the battery and wait for 15 minutes. Reconnect the battery and drive the car for atleast 5 kms so that ecu learns the engine parameters and recalinerates all the sensor, by now the performance on petrol would be excellent.
Now you have to recaliberate the emulator to set the correct timing advance, and TPS postion sensor in emulator and also set your emulator to dynamic advance now tune your car on CNG and you are done
If you dont know anything about engines than ask some mechanic to do the job but you will need two of them first one to set the car on petrol and the other one to set the car on CNG
For CNG I would recommend maverick petrogas just say them to caliberate the emulator