Empire asks great stuff yeayea
i'll try to help a lil here...
I swapped this ka in b/c the one in it knocked BAD! It came from nizm0 Matt's car,test drove it b4 i bought it,he will vouch for it as it was auto and he used to drive his bone stock s14 just as a dd to work+home. It was swapped out for an sr not b/c it had probs.

It ran/idled great so it may be the bad gas or bad luck of one of the following you guys mentioned:
-headgasket
-o2(i advised it be changed)
-temp sensor(I advised to be changed)
-cap+rotor dont know mileage of them,etc...
-tps
-injector o rings
-It didnt have any vacuum leaks but anything is possible

it does smoke when you let it idle a while and then press the gas which obviously points to valve stem seals(Which i told,advised,even bought and gave to him)

It should have antifreeze/water mixture
Has brand new BKR5E's
Has brand new Felpro valve cover gaskets that leaked on the outside when i showed him the car. Has anyone ever had that happen? I torqued in sequence accordingly etc...wierd, never happened to me before ever.

I drove it around for like a week and a half and when i got back i would let it sit there and idle for 5-20 minute intervals to look around for any other leaks,noises,problems,etc...especially after I changed the front main. So no probs, no leaks whatsoever and it would sit there and idle perfectly,no temp issues,never ever died/stalled. It did miss a couple times but not bad and was not a problem. Sure hope you figure out the problem Richie, its a good car+motor.Let us know what you do and how it works/affects things.

I still need to come get that wing,lol,ill call you soon.

btw this should be in tech not lounge but tis fine