Short history: Had #3 misfire, replaced the coil and then the plug. The plug was the problem. After looking at how bad it was I decided to replace the other 7.

Now #4 is misfiring, intermittently, more often when going up hill or under a heavy power, (picking up speed on the on-ramp). The engine light will flash several times and after doing this several times it will stay lit. It was fine before I messed with it, so I must have screwed something up. Swapped the new coil on #3 with #4. #4 still misfires. swapped the plugs between 3 and 4, same issue. Replaced the coil connector on #4, and the last thing was to swap the fuel injector between #3 and #4. I don't think I touched the coil injector connector when I swapped the plug so that is the only reason I haven't replaced that connector.

I"m out of ideas except taking it to a mechanic.