BMW fuel filters are very efficient. So efficient that they can become clogged quite quickly. Here’s a few tips to work through some common fuel filter clogging issues.
Concerning gasoline leakage from a BMW fuel filler, I too had a similar problem. The gas cap didn’t form a tight seal due to a 1/8 inch gap between it and the filler neck. Here’s a checklist to help solve the problem.
Try this Mercedes Benz fuel filter upgrade.
If your 2002 is loosing power, off and on, here is the one item you might overlook.