I own a 1999 Oldsmobile Alero V6 Automatic. Sometimes when accelorating car will act as if I am pushing and releasing the gas feed quickly, for example as if someone was slightly accelerating at a stop light to show off. I have replaced the throttle positioning sensor, all ignition coils, plugs, wires, did an oil change, one month I ran stp fuel system cleaner through and when that didn't seem to help, I went out and bought Lucas fuel system cleaner the following month since I knew it was better quality. I also had diognostics performed at Auto Zone and they also listened to the motor and both checked out fine, besides a code for an o2 sensor which the guy said wasn't even off enough to cause any problems. The check engine light is not on and does not come on when car acts up. Also I am not sure if this is related to the main concern just stated, but sometimes when I start my car the rpm's wont stay up high enough and the car will die out within the matter of one to two seconds, but if I start the car and rev the engine for just a second it stays started. Any ideas?