My 09 R1200RT was stalling more and more often, and no simple maintenance could solve the issue : TB sync, TB cleaning, idle actuators clean/ swap.
Thank to Tinderairbox video
   • Throttle Position Sensor Testing On B...  
I decided to investigate the TPS sensor. I found out that near idle (throttle almost released) , the TPS sensor was delivering out of range resistance value.
a swap for a good condition used part did solve the problem.
hope it will help people who encounter the same idle issue !