BMW: 1985 BMW 325E, vacuum leaks, replacement gears

Question
I have an 85 BMW 325E that has several small issues. First off, the odometer is stuck at 116,947 miles.  Not sure what the actual may be, but I would like to fix this. What I need is a place to find either a replacement, or the wiring or what to look at under the dash to maybe repair this.  Second, at idle the car hunts for an appropriate RPM. Worse when it's cold, but it still does it while it's hot too. Why would this be?

Answer
Donovan,
 The Odometer's are notorious for failing in these cars.  Fortunately it's not an electronic problem (providing your speedometer still works).  The Odometer is driven by several small, plastic, gears that are driven by an electic motor.  These plastic gears will literally turn to "mush".  I've had this happen on one of my cars, you can touch the gear and easily break teeth off of it.  However you have 2 options for replacing it.
 (1.) Buy a spedometer off Ebay and try to get one with close milage to what you have, and drop it in your cluster.  Check on your cluster and see who made it first, there were two companys, MotoMeter and VDO.  I would say that the gauge would work in either of them, but I'm not 100% sure on it.
 (2.) the second option is to go to www.odometergears.com and buy replacement gears.  I think these run $25 or so.

 If it were me, I would replace the gears.  If you buy a used speedometer, and attempt to remove those 20 year old gears and replace them on your speedometer then you are likely to break them, and you will still need gears.  Second if you just use the whole speedometer you bought, it STILL has the old original gears, and they are likely to fail at any time.

 As for the engine surge, there are MANY possibilities.  I would check for vacuum leaks first.  Take a can of starting fluid and LIGHTLY spray around any rubber hoses.  if you hear the idle go up, you have a vacuum leak.  Fix the leak.  I've also known the coolant sensors to cause problems on these cars.  These are located in front of the fuel injectors. there should be 3-4 of them.  One of them is the sending unit for your temp guage and 2 of them are for the ECU to know when to turn the fans on, and when the car is up to temp.  
 Check all of those and let me know what you find

 Hope this helps,
 Josh