Ok I have a 99 infiniti g20 touring model with the sr20 de motor. 4 cyl frt wheel drive. When the car is cold it has power surges, strong smell of gas and black smoke from the exhaust. But when it warms up it runs perfect. I have replaced the spark plugs, wires, coolant temp sensor, vac lines, throttle posistion sensor, gas cap, radiator cap, mass air flow sensor, and air intake and complet exhaust to include new catalytic converter and o2 sensors. I'm out of a clue to what it is.