We just finished putting a 1st gen b16a longblock in my LS, using my LS clutch and harness and converted the motor to OBD1. The motor turned on right away, but it revs to 5k at idle. Its not the TPS or MAP, we unplugged those and it still did it. VTEC and the knock sensor arent wired up but we were using the LS ECU so it doesnt matter at the time. anyone know what it can be?

 

Not to sound redundant or stupid... but did you maybe reverse the tps and map sensor plugs?
They have the exact same plug, i made this mistake also, who knew honda would do some stupid crap like that.
Swapped em around and bam idles at 1500 when cold now... it used to idle from 3k up to close to 5k then start going crazy.
Try it and see, i feel stupid for not thinking of it sooner, but this was in a 93cx with a 94 ls motor.
Good luck, if that doesnt work maybe the iacv is bad?