Hello and welcome to JustAnswer!
It does sound like it would be the number 5 and 6 coils. The codes should have been in the form of P0355 and P0356. These shouldn't be bad to diagnose. You should be ok with just a test light. Unplug these two coils. Start the engine and check for power on the dark green/orange wire. If it's ok, check the other wire in the connector for pulsing ground while it's running. Put the alligator clip on battery positive, start the engine and probe the second wire in the connectors. If the test light flashes and you found the 12v feed on the first wire ok, replace the coils.
It did this a couple of weeks ago, but after stopping the engine and restarting it cleared up. Todayit want clear up. Is it unusual for two coils to go bad at the same time? we have been having 99 and 100 degree heat for the last couple of weeks, would that be a factor if the coils were weak? Thanks
I checked the codes and they were PO300, PO355 and PO356 primary and secondary ignition coils. I then unplugged them and ran the test with the tester both plugs had a constant 12 volt and a pulsing ground. I then changed out both coils. I cleared off the old codes and ran the test again, as soon as I started the engine the check engine light light came on and the two diagnostic codes re-appeared, PO355 and PO356. What can I do now? Thanks
Have you pulled the plugs on those cylinders?
I'd like to get a look at the plugs, and while the coils are back out check for spark on these cylinders. Make sure not to dry fire the coils because you can take out a coil driver (if they're all still good anyway).
Another thing I'd like to make sure is that you replaced the correct coils. The left bank (driver's side in the US) is the odd bank, right bank is even. Number 5 is the second to last cylinder back on the left side, 6 is the second to last on the right bank.