hello everyone I have a 2000 audi a6 4.2 and im having problems starting the car after it warms up. The car starts up fine when its cold but after a 30 minute drive, the car cranks but wont turn over unless i give it some gas. After it starts it kind of hesitates like maybe not enough fuel or air. Im not sure what it is but after a few minutes of driving its fine. I have changed the air mass flow sensor but same problem .Does anyone have any idea what it could be i really dont want to take it to the dealership $$$$ please help .