How do I adjust my front derailleur on a full suspension mountain bike?

I have a full suspension mountain bike with a 3x9 drivetrain. It has front and rear Sram derailleurs. It was having issues with ghost-shifting and since tune-up appointments at the bike shop are scheduled months out, I found the manuals online and have adjusted them myself. The ghost-shifting is gone and when I have the bike in the clamp front and rear both shift flawlessly. However, when riding it, it will not shift on to the largest cog in front. I’ve tried the barrel adjustments and it’s not helping. Is there something I’m missing? Should I adjust the derailleurs with all the air out of the rear shock? If so, why do no YouTube videos or manuals say to do this? I just don’t get how it works flawlessly when in the clamp, but riding it won’t shift right. Any thoughts? Thanks