Strange Idle issue

95 caprice wagon
133K miles
new opti, plugs, wires, water pump last summer.
Air pump deleted.
it was in the single digits out, but the car was fully warmed up.
i came to a stop and the idle dropped almost to a stall, the voltage gauge dropped - it came right back up, but did it about three more times before it smoothed out.

this happened about 6 more times on my ride home.
when i went to back into the driveway, it dropped again but this time stalled.

i can get it to do it in park by blipping the throttle.
it has done this on two separate days, but not today.
any clues?

Leaky EGR? Vaccum?

Check the fuel pressure. The ammeter probably has nothing to do with it, it is just reporting that the alternator is not spinning fast enough to make sufficient voltage.

Also check the computer codes. If there is something happening to throw a code, you want to know about it.

You can also check your coil and ignition module, although it sounds more like a fuel problem.

Finally got around to looking at this.
picked up a new EGR gasket.
pulled the EGR off and there were two very toasted gaskets under it.
cleaned it all up and installed the new gasket, so far so good. seems to be running smoother too.
tomorrows commute should tell me if that solved it.