I have a 1988 Audi 90 Quattro. When the car sits for an hour or so, it runs perfect. About 3-5 miles after driving it, I will come to a stop and it will stall. Almost as if it is losing power. After it stalls, it takes a couple minutes to start it back up. Once it is started it chugs in every gear while going down the road, and tries to die out. At this point I have to have the gas pedal to the floor to keep the engine running. I have replaced the fuel distributor, and the fuel pressure regulator. Both OEM. The fuel pump has pressure and runs fine. Maybe the fuel pump is shutting off? Also, the previous owner said it could be a vaccum leak. I'm not sure where the vaccum hoses are located. This car is my daily and I love it. I need it fixed ASAP!! If anyone knows what the problem could be, PLEASE HELP ME OUT!

Thanks -Ross