For some reason... My idle wont stay consistent day to day. One day it will idle fine at 750 in Park next day it idles at 500 and next 1000. Having the headlights and blower on decrease rpms by about 100 so I lways adjust it at temp with everything off. I think the hot idle screw spring may be weak and backing out. I took a pic of where it is. After a few days or the next time it acts up I'll compare. I may have a vacuum leak as well... I had like 16" of vacuum and it doesn't fluctuate more than 1.25" (276/281 adv dur 112lsa) either way. I guess if the idle changes without the screw moving that will infer a vacuum leak. Or potentially timing jumping/sticking. I'll report on my findings in the coming days.