Vikram, It's more likely the O2 sensor. Try moderate acceleration when the car is cold... as in the first 45 seconds or so of running, if it doesn't surge then it most likely is the O2 sensor. ( The O2 sensor isn't used until the engine warms up a bit......) If it does surge, I don't know what it would be. Somebody else here my know better than I..... Mike L.