1995 Mitsubishi Montero poor idle

1995 montero suddenly maintains hi idle in cold weather, ie, will not resume to low rpm after rapidly engaging accelerator pedal. It remains at 2000-2200 rpm until warm.
At the moment, 75-85 F ambient temperature, it will not idle at specs when engaging the air conditioner. Tach shows 500-600 rpm. Prior to warm-up, (3-4 min idle time), the engine continously lopes and eventualy quits.

Any suggestions?

Thanks for you professional efforts