Chipper/shredder with 18 hp vanguard. Bogs down when under power. When run without the air cleaner it chips like a champ. Put air cleaner on and it will almost die under load. Ideas?

P.S. The air cleaner has been replaced.

Hi,
Even though the air filter has been replaced, it sounds like it has been contamintaed with gas or oil.
Peace,
Clarke