My 93 rx7 is surging at idle from 1200-2000 rpm. This is a fresh motor with a new standalone ECU. I've done the following things to troubleshoot:

AWS is removed and blocked off
vacuum nest is removed and blocked off where appropriate
EGR is removed and blocked off
fast idle cam screw is removed (same problem with it installed, no difference)
vacuum leak test with fog machine
vacuum leak test with spraying carb cleaner around possible leak points
vacuum leak test with propane around possible leak points
checked IAC wiring
checked IAC PWM settings (244hz)
checked TPS wiring
checked TPS settings
checked that the spark plug wires are going to the right spark plugs
checked coil wiring
checked injector wiring
checked fuel pressure
played around with TB idle bleed screw (adjusting made NO difference)
tried adjusting ignition timing from 0-40 degrees at idle, definitely a difference in how it sounds but still surges the same


Any ideas?

 

Could be a zillion things. Could be throttle plate needs to be closed. Could be IAC duty too high. Disconnect IAC and see if it drops. If it doesn't, close primary throttle plate.

Could be poor fuel tuning causing misfire.