You are starting to get in over MY head here but fwiw, here is my take. The firing order on that motor is 15486372. So injector pairs 1/5, 4/8, 6/3, 7/2 fire in their respective order. If there is a bit of overlap in the EFI switch point, then 1/5-4/8, 4/8-6/3, 7/2-1/5, could overlap in your static test. 1/5-6/3 and 4/8-7/2 should never occur, as you observe. The actual pulse to the injector is quite short compared to the interval between triggers when the motor is running.

It's not hard to unbolt the injectors and pull up the ring line and injectors out together. You can then observe what the injectors are really doing with the fuel as you crank (collect the fuel using some kind of containers, preferably clear so you can see the spray. Careful, pull the coil wire off and far away to avoid ignition! If the rubber hoses on the ring line are old and cracked (common), good time to replace them now.

You can also use a 1.5 volt battery to manually test each injector (don't use 12V, these are low-impedance solenoids!) The injector should "click" and the pintle should open and you can spray fuel/solvent thru the injector.

Could try swapping injectors 1,3,5,6 with 2,4,7,8 & see if problem also moves.