Saab 9000CS is sporadic… ???

Hello dear community. You have already helped me with my last problem wonderfully. Now I have a new problem. I ran to a traffic light a few days ago and let the car roll up like I always do when the traffic light shows red. When I hit the brake the engine went off. It took several times to start the engine again. Then he came quite hesitantly and “swallowed” himself again and then he ran again as usual. Had the Pro Then the tank cap changed, because it probably left no more air in the tank. After that the car drove without any problems until this memorable event. Where can I start with the troubleshooting? Have the petrol pump in suspicion, since the tank indicator from approx. 35 liters indicates something very imprecise. This means that it moves from a level of approx. 35 – 40 liters jerky against zero. When the engine went out the tank indicator showed approx. 20 liters and After starting, the display dropped to reserve. After that, I filled up a good 30 liters and the display went to 60 liters. Quite strange the whole thing. Can it be that the petrol pump sucks air from a certain tank content? I am, as always, a grateful customer for your answers. Greetings from Ralf