Two ways to do this. I suggest paying for a diagnosis and then post the results. That input will generate responses from those with similar problems and what the problem ended up being. Sorry, can't help you with a local Indy shop, Texas is big but still not close to you. If that is something you would rather not do, please post more about the circumstances---cold or up to temperature, always/sometimes, shifting normal otherwise or not, check for codes or not. Does it upshift normally under hard acceleration and the problem is the upshifting after? There are strong feeling on both sides of changing or not changing transmission oil. I change oil about every 50,000 mi. I have 107,000 mi. on a 2002 4.6 with all Dinan mods from the beginning, and, for the last 3,000 mi. a 150 shot of nitrous. Transmission is shifting the same as it did when I drove it off the showroom floor. That said, I don't think you will correct your problem with new fluid. My position is to change fluid is on a regular maintenance schedule rather after problems are showing and if you are having problems get a diagnosis and second opinion which you can get at least close to that here. As is, responses to your symtoms will range from a little duct tape will fix it to the problem will cost you more than both our X5s are worth.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas