Tranny doesn't stay engaged when stopped at idle.
 

my car is 2002 Volkswagen Golf, rlbryt.This occurs only after engine is up to operating temp. If I quickly pat the accelerator it will reengage even below 1k rpm. Change the fluid with the proper synthetic a short while ago but it did seem to change anything. What am I looking at for a probable cause and cure?
if i want to solve it by myself, does the dp3 odometer programmer can help me?