lolzzzz....Im sorry to say bro you are another victim of a misinformed cng guy.....!
blocking air supply whether it be 40% or 10% is a sure way to making a donkey cart out of your car.
CNG is very sensitive to airflow changes, and evidently it changed a lot when you replaced your air filter.
The correct way to go about it now is
1: remove that blockage, return it to normal
2: inspect that all clips are tightened on cng pipe that goes from cng regulator to somewhere near your cng venturi just below the air filter.
3: Make sure the air filter sits tightly on the carb throat - air should not leak/ bypass air filter into engine.
4: Tell a cng guy to give it a proper cng tune-up, it hardly takes one minute.
OR you could let the car run as it is, it will surely die when you switch on the AC, or when you convert to petrol. And it definitely wont rev as high and as fast as before. Trust me, unfortunately i've been down this road...