It don't happen at any specific times seems to b worse when under a quarter tank of gas I replaced the spark plugs. When I press the pedal to the floor it only gets to 4000 rpm and no faster than 40 mph it still stutters then after a few seconds to a minute the rpm go way up and its fine sometimes ir will do it again rite away and some times its good for a while and the engine light comes on sometimes and goes back off
My 95 a6 quattro stutters and dies unless I press the gas pedal to the floor on 1995 Audi A6 Quattro
My best guess would be to have the fuel filter changed. Sounds like you are picking up dirt. Also you might try a bottle of heat in your tank when it is about half full. Then see if it happens when you get to a quarter of tank. If it does not happen it means you had water in your tank.