Just to share,from my experience....
If your engine was from halfcut shop, try to check the fuel filter...Maybe it got clogged & need to be replaced ....In my case, i've changed my engine to halfcut one last year, but have not change the 'fuel filter' since then...The only thing i changed was the ficd for AC & tb....My problem exactly like you guys, after engine is hot & AC is off ,my engine can easily stall...Eventhough, i've change the ficd, the engine rpm can be said steady only whenever AC is on....but not when AC is off (especially while engine is hot)....So, i guess there is not enough fuel coming thru the tb during idling due to the clogged 'fuel filter'....Which caused the rpm to behave like that one...After 5 days, it seems my idling become okay already ;)
just my 2 cents...