hi the car gti t mk4 golf when stopped warm at tick over is cutting out then wont start for 20 min then starts and runs fine until next time ,today while sitting at lights the car ticking over fine i pressed for the air con to come on and the car instantly died and the same problem arose where it wouldnot start and had to be left for around 20 min and then started ,,does anyone know what this is ,,mythought is there is a noise from the fuel pump when it starts and the pump may be on its way out thanks john.