I have been driving my car more often since i have off from work for a few weeks and this issue is really starting to worry me because the engine will stall or sound like it wants to stall and il loose steering and brakes

the engine runs perfect this symptom only happens when i am driving on the highway for a while and get off the exit i slow down or downshift and the engine just drops really fast and almost wants to die if i dont gas it.

Why is the engine IDLE dropping so quickly? What adjustments can i make to compensate for this? with the 116 update the engine idles smoother and much lower in the RPM that it ever did with the earlier 114 update. I raised my RPM 150 more but this did not help. I am not using timing control yet. I have not touched power enrichment setting from the factory setting, What can i do?