While idle the cars engine turns off. The car chugs if accelerates.

What is your question?

While stopping at a light the car engine shuts off. If pulling into a driveway the car engines shuts off. If accelerate between 40 - 50 mph it chuggs but once past 55 mph the engine runs smoothly. If it is cold outside the car starts without a problem if it is humid this does not happen.