Soooo, I just added another brick to the collection ⏠ 242 na-b23] and cannot get the dang thing to idle smoothly. This is after swapping in a known good AMM from a well running b23, replacing the AMM to throttle body hose, cleaning the TB and new gasket, new intake manifold gasket, checking all vac hoses, cleaning the idle air motor, and giving the air box a new thermostat with cleaned/oiled flapper workings... Wiring harness is superb compared to some we've all seen and the TPS clicks like it should...

It's worse when warm.

Um, now what?

Interesting: noticed 3000 rpm brings a sudden jump in power [and quite a peppy turbo-esque one at that], sub-3k is a tich on the sluggish side side of normal; could this engine have a custom cam grind of some kind that I wasn't informed of and the idle just gets to stay funky? Or is something else still miscalibrated?

Ideas?
Thanks.