I have a 98 A8 with 142K on the odo. Just recently coming back from a long trip I came out of the restaurant to start the car. It cranked over for about 10 seconds, then finally started. Once it started, ther were no additional problems and ran fine. It has done this for several days now, usually only when it is cold. If this engine is warm, it usually starts right up. Is this a fuel pump problem, pressure regulator, etc. Any thoughts or advice would be appreciated.

Thanks