1 and 5 is 1 group of trigger points.
4 and 8 is another
6 and 3 another
7 and 2 another.
Because your BANKS (groups) are not firing, it's most likely your trigger points. They are NOT the igniton points (visible when removing the distributor cap). They are the points with the wiring harness on them on the left side of the distributor.
See #5 here. There are 4 sets of points in here. 2 on the top of the plate, 2 on the bottom. Clean them out. Peter suggests carb cleaner, I suggest carb cleaner followed by an index card run through the point of contact (NOT SANDPAPER!) - this will clean the gunk out and quite possibly restore those 4 cylinders.
If you are really down 4 cyls it must be running like absolute garbage! I'd hardly call that just a lumpy idle!
Edit: Also, test for continuity in them using a multimeter (I assume you have one!) - the pin diagram is probably on that D-Jet manual I sent you a while back but, if not, I can check the spare set I have.
Your trigger points may look like
these without the cable or
these with it.