First time poster here, not a mechanic by any means so bear with me...

Recently on a trip home from out of town, I noticed that there was a light on my dash indicating that my cruise control was set to 40.5 mph, which was odd. A day or two later, my EML light popped, and I could tell the vehicle began to limp. I made it home, and my friend brought over his OBD II reader, and I went out to pick up some spark plugs because I could recall the the car had recently been kind of "jumping" when I would initially start the car, RPM's fluttering as if I were tapping on the gas pedal and it felt like one of my plugs might've finally given out on me. His reader, popped up a couple of different codes, so we cleared them out a few times in order to see what would stick and got P0123 code, which according to the app, was showing my throttle output at 90+mph, and P1632. After doing some loose research around the internet, I gather that I probably need a new Throttle Position Sensor. Scoured the internet all day in search of some kind of youtube video that would lend assistance, to no avail. However, with my new knowledge, I found the MAS and Air Filter and worked my way back to what I deduced MUST be the TPS due to it's location and appearance. I have managed to remove the thing from my vehicle, and was pretty proud of myself given how close to the engine wall it is, and my lack of time previously spent beneath the hood of any vehicles. My issue now, is that I've called around to local part stores (no bmw anywhere near my new town, thanks to my husbands military orders which have landed us in Mississippi) and everyone just says that the part is not serviceable, and that they do not have the part available. What am I missing?