Liana missing on petrol. help required

I got a Lia 2007 lxi sports with after market cng. I bought it about an year ago. No problem since then. Just routine oil change and nothing else. About a month ago, I started experiencing that on petrol, on acceleration, it first dips and then starts accelerating. Yesterday when i started my car, it refused to take the paddle, started missing rigorously when I press the paddle and refused to move. Then after trying pressing the accelerator for 10 minutes, I managed to convert it to cng. The car was very much fine on cng. No problem at all. I drove to my mechanic and told him the whole story. He instantly said that it is the fuel pump problem. I asked him to check thoroughly. Then he detached the return petrol pipe and block the return petrol. As a result, the car became so smooth as it was on cng. Then he told that there might be a problem in the retun petrol vaccum. I said him good bye and told him to visit again. I was very much confused, what to do and what not.

Today, in the morning I visited suzuki mini motors at Gulberg. After a check up of 5 minutes, they told that apparently there is no problem with pump or return petrol vaccum. But you have to spare some time, we will first check it's tappet. Repair if required. Then we will check it's coil. Then we will check it's sensors and injectors. And then we will check it's fuel pump and vaccum and then we will finally able to tell what the problem is. After hearing he whole story I was about to fell down. Said good buy to them and left for my office. On the way, I recieved a call from my friend who referred me to Suzuki ravi motors on bund road. The I went there for the checkup. The supervisor there, after hecking the car for about 2-3 min and listening to my whole story, told me that all of the previous diagnosis are wrong. There is nothing wrong with fuel pump or he vaccum or the tappet or the coil or the sensors or the injectors. My cng advancer or emulator are causing problem and he suggested me to visit a cng elctrician. After too much confusion and disappintment, I visited the cng electrician and told him the whole story. He thorouhly checked the emulator and advancer and told that both are ok.

After this hectic experience, I reached back my office with too much confusion and disppointment.

I am really too much confused. Could not rely on any of the diagnosis. Liana or other experts, please let me come out of the situation and advise about the correct diagnosis.

Anxiously awaiting for you help.