I have a 1989 Porsche 911 Targa...I have a problem in the morning when it is cold. After starting the engine I normally wait a minute than drive. My Porsche starts a jerking motion or bucking like a horse when I step on the excelerator and let up off the clutch. I sometimes have to pull over, turn off my Porsche and wait a minute. I replaced the Fuel Pressure Regulator and the Air Flow Meter Sensor. I am still having this same problem can anyone Help!