MicroSquirt.com read only forum (Jan.15,2018)

Some injectors have a screen inside as a final effort fuel filter. If this is clogged, the injector could pulse, but nothing will get thru. However, I would also troubleshoot the injector harness to make sure that particular injector is getting a signal. A resistor and LED are all you need.

While it would seem necessary to plumb the IAC so that all cylinders are equally affected, you could control idle by just adjusting one set. Just as the idle can be (incorrectly) set by turning the idle screw on a single SU, the same effect would be available by just adjusting idle air on one TB.

Is your distributor itself in phase? You could be firing the ignition perfectly timed, but the rotor will not be pointed at the cylinder. That could account for why it runs better when the trigger angle is changed.

You can verify by getting a spare cap, making a hole in it so that you can see the ...