that's the symptoms of aftermarket cam / phaser limiting w/ a stock tune or a canned tune (for stock engine)After install these were my symptoms.
Cold start: car would start right up with the stock tune. Idle and rev fine for the first 60-180 seconds. Than would try to die. You would have to push on the gas pedal to keep it running like a carbed vehicle. if you tried to put it into gear it would immediately die. If you gave it gas while shifting to keep it runnin, it would put the transmission into like limp mode until rpms drop to 650-800 than engage transmission. You would have to flutter the gas pedal to keep it running.
it will cold start then idle will drop down, surge and stall. then difficult to get to idle w/o constantly giving more throttle
proper tuning will get idle correct