Computers get the blame for a lot of issue that may not be a computer issue? Just saying.
Most pcms will not keep throwing the same codes, so lead to believe the issue is ,(wiring issues) or mechanical controled!
Misfire could comein the form of injector, easy to see , just remove one from another cyl and put in that hole, if it stays on 6, then not the inj! move to next item
switch wires to the plug, etc,
change plug the same way , time consuming, but xcheaper than throwing money on items not needed!!