Been running on 89 and 91 to help clean the carbon buildup and potentially fix a misfire in cylinder #1. Does fuel grade really change or clean I mostly use chevron/shell/Arco gas.
2006 V6 Mustang
No. If you have misfire, you should find out why it happens. Using higher octane gas does not help in cleaning injectors.
Been trying to find out what’s the issue the only thing I changed is going from 87 to 89 so I might go back. Hopefully that fixes it enough so I can get it checked out.
Octane rating has no effect on carbon buildup. Even if the higher octane gas has a bit more detergent it's unlikely to have much effect. You might want to consider the ATS Carbon Clean product that Scotty has talked about.
https://www.atscarbonclean.com/
https://www.youtube.com/watch?v=cz1T6hh1sgs
Been trying to find out what’s the issue the only thing I changed is going from 87 to 89 so I might go back. Hopefully that fixes it enough so I can get it checked out.
Using higher octane gas is not going to "fix" anything. Aside from any carbon buildup issue that may exist, your misfire problem needs proper diagnosis. Check the easy and simple things first like spark plugs and vacuum leaks. Other than that, scanning the car for codes and live data might point you in the right direction.
I replaced spark plugs and cables as well as coil pack. Code still PO301
I replaced spark plugs and cables as well as coil pack. Code still PO301
You have to dig deeper. Anything that interferes with normal combustion can trigger a misfire and there are quite a few possibilities. Vacuum leaks would be a common issue, especially on a 17-year-old car, but it could be also be caused by issues with sensors, computer modules, wiring, or even engine compression. Have you analyzed live data?