I recently purchased a 2004 A4 1.8T Quattro. All of a sudden it has started to idle rough and have difficulty at take-off from a stop. Once it reaches about 20mph or is revved hard, the problem goes away. It appears to only happen at a stop or after start. Anyone have any tips as to what direction I should go to begin to fix this? Once on the road, it runs perfectly, and often the problem goes away until the next start up. Also, when I fill it with gas, it has a hard time starting (has done this every time I have fueled up).

any codes???? or check engine light on or flashing?

No check engine light. Have not run any codes, will do that today. Problem seems to be getting better, but still present from time to time, beginning to think it may have been bad gas.

have u heard any noise from the rear of the car. If so that might be the fuel filter. Though i would inspect your vac lines for tears or the check valves for corrision.