I have a Ryobi 790r that starts up fine in the choke position and runs in the partial choke position, but when I advance the choke lever to run mode, it stalls out. The fuel is fresh and mixed properly. Spark plug is clean, new and properly gapped. What do you think is the problem? Note that I am handy and service the unit myself annually.

 

They usually need a new diaphragm when they have that problem. If it has had the carb rebuilt in a number of years I would just put the entire kit in it.

You may get it to go by turning out the low rpm screw just a little.