Re: Ryobi ry08548 leaf blower
One that carb, during the rebuild, did you pull out the high speed and low speed jets and clean those and the seats? Sounds like a problem I used to have, I rebuilt a Zama carb and it sort of ran but eventually once it was hot it would lose power and die. There were EPA plastic locks on the jets to limit adjustment, so I had not touched those during the rebuild. I finally decided to cut the lock off and properly remove and clean the jets, and that solved one problem but caused another (until I figured out how to properly adjust the jets).
If you have not done so, screw in the jets and count the number of turns needed for each until you bottom them out, right down that number, and then pull them out and clean clean clean. Put them back where you found them and see if that solves the problem.
You may need to find the factory carb adjustment settings to make sure you properly set it up.