SR20DET Z32 MAF swap issue HELP!

[CurtisCh]

i've got an S13 with an SR20DET in it.
just picked up a GT2871R turbo, 740cc injectors, Enthalpy tune ECU, z32 maf
I bought the whole set up from a guy in the states that was running it on his s13 as well.
Put everything in the car and went to fire it up and the car runs rough at idle (5-600rpm surging) with MAF harness plugged in.
When you unplug the MAF, the idle goes up to 1200 and holds smooth there. Seems to run better unplugged.
I've checked on the ECU and it's not throwing a code for the MAF either... I've double checked my wiring for the MAF harness and from what i've read online, it looks to be sound. only thing i did was take the 2 black ground wires in the center of the z32 harness and tie them together into the single black ground wire on the s13 harness.

If anyone has any ideas of what to try next, or ever ran into this problem, help me out please! thanks much