jfoj, you're on duty early this morning!
OP, the bouncing idle you had been having sounds like it could be icv, of course, and that would cause your stalling. Did cleaning the icv have any effect?
Have you checked the vac lines behind the intake manifold? I know you said you replaced all hoses, but wonder about those?
Anyway, I really do think you need to get codes read. If it's none of the usual suspects, then I'd think codes might point to some sensor or the like.
Have you done any 'non-stock' things to your car you didn't mention? After your engine swap, was your car running good, or did the bouncing idle happen right away?
I'm so depressed. No one wants to come see me in NYC: Sat, Oct. 8, 6 p.m. at Greenwich Village Comedy Club.
Mangofy your E46!