My ultra was stalling off and on at idle. 27K miles. I perform my own maintenace so I know it was done properly. After a lot of reading in the forums, I gave the engine temp sensor and fuel filter replacement a try. Hasn't missed a beat since. Even seems to run better. Could be the rider just feels better not worried about stalling.

Fuel Filter 61011-04a $21.50

Engine Temp Sensor 32446-99 $37.99

Engine Temp Sensor - all you need is to swing the horn forward and remove with a socket and a very long extension.

Fuel Filter - Make sure before you remove the locking ring, you clean around the opening. Don't want excess trash falling in there. I used my compressed air blower and a rag.

Both jobs took me less than 30 min.