Took the car again back to my mechanical engineer. Tested the car and it seems to accelerate fine. The problem is in the deceleration. When coming to a stop sign, slowing to make a u turn or traffic light the car tends to lower the revolutions from 1,100 to 600 tends to stall but immediately goes back to 1,100 RPM. THis is not normal, something is wrong here. After a couple of tests the needle now reads empty on the tank and the car is now shutting down completely even though there is still fuel present in the fuel filter (mine is a glass fuel filter which can show any impurity in the line). The engineer did tuned up the car and changed all the spark plugs in front of me. Do you guys think i can solve this issue by myself or should i take the car back to him again? We are thinking on replacing this Far 311 race came with the Original Stock cam so i can get a smooth idle and use my car as a daily driver. THe spark plugs are getting dark in traffic jams due to the race cam. I want to solve the stalling and irregular RPM drop when decelerating first and then swap the cam. Can anyone advise me on how to tackle this problem?