just an update
my mechanic fixed the idle and restored it how it is supposed to be
the car starts up differently, shuts off differently, and drives a lot smoother.
when the air conditioner turns on there isn't a sudden jolt in the car as there was before.
we also had the engine in the 5-6K range and allowed it to drop in N, and i did observe what you were saying about falling past 750RPM.
i never noticed anything before so i cannot make an accurate comparison but what happens now from 3rd gear and 5-6K RPM, when we throw it in N, the RPM needle hits 1K and then bounces and slowly bounces until it adjusts itself to an idle RPM.
thanks for all your help.

only one problem though i think we have a vacuum leak somewhere because SOMETIMES when the car is idling, it jumps from 1K to 1.5K RPM but then remains calm.
there is not specific situation that causes this happen, it only happens sometimes and only at a stop.