Not firing on cylinder 4 and 5
3 days ago I parked my ZJ and it was running fine. The next morning I decided that I was going to treat it to some exhaust work at the local shop. It had developed a misfire overnight. I drove it a couple of miles and it got worse.
Started by pulling the spark plug wires to determine which cylinders weren't firing...4 and 5 were the issue so I pulled the plugs and they looked worn out (brownish color and very large gap). I replace all of them and it didn't fix the issue.
I then checked for trouble codes and got code 27(Injector #3, and/or 4, and/or 5, and/or 6 output driver does not respond properly to the control signal. )
Next I looked at the injectors. All voltage and ohm measurements checked out but I still pulled the injectors and threw in 2 that I got from the local junk yard just in case. Still has the same issue.
I'm not sure where to look next. Any suggestions?