91 GS-T Misfiring

I was data logging and noticed a misfire. I looked at the logger and turned off each injector until I got to #4 and it made little or no difference. So I replaced the injector and it did not produce any results. When Listening to the exhaust, I can hear where it sounds like there are two intermittent misses. I bought plugs and wires previously so that doesn't come into play right now. I then bought a spark tester to put in the end of the plug wires, one at a time. at .010 and at .020 each fired consistant with the other. When I checked then on .030, #2 and #4 were intermittent. So I assumed it was the coil. I took the shortcut by not shelling out $191 on a new coil, so I picked up one at a salvage yard. I put it on and there was no difference.

I don't know what else it would be causing two wires to not hit like the others do unless it is a very odd cioncidence that I picked up a bad coil. Would this be ECU related? It didn't do this after I rebuilt the head and put it back on, but started when I was data logging it.

Any help would be appreciated.

Thanks,
Greg

What do you have the gaps set at on the plugs?

The plugs are a 6ES gapped at .032. I'm testing the spark before it gets to the plug at the end of the plug wire with a spark tester I got from Advance Auto. It was okay across all 4 until I got to the third step in testing. The plugs shows to be burning good and brown too.

What do you have the gaps set at on the plugs?

regap them at .028