My advice-

(1) read the "New Lawn Equipment and the EPA" thread to gain insight into why it runs like $%^&.

(2) if it is useable at all, mow with it. When the air cleaner gets a bit dirty it may improve, the restriction of the air cleaner will richen the fuel/air mix.

Most newer small engine powered equipment I have used in the last 5 or 6 years runs like yours probably does, i.e. just barely well enough to use.

Thank you, will read the thread.