HEY EVERYBODY JUST THOUGHT YOU MIGHT BE ABLE TO HELP ME OUT ON THIS ONE. i just bought a honda crx si 1988 with 115k on it about 3 months ago and i have this really annoying idle thing thats driving me crazy!

it idles corectly during warm up
when warmed up though this is what it does
its rpm sits at that first line below the 1000 mark on my stock rpm gauge
it seems this would be right but the steering wheel vibrates like its idling to low.
sometimes it will idle really low like at 300 rpm or something for a couple seconds and then it will pop up to 1000 and return to that first line again.
other times it will idle at like 1800rpm and wont stop for a while but when it does it normally wont do it again for a day or two.
ihave taken off my eacv and cleaned it , nothing changed
i have looked for vacuum leaks but i may not be lloking in the hard to find spots
im wondering if i can buy a new eacv at the junkyard, and if so which year and model can i take one off of?
any suggestions would great thanks jc