Thanks for the reply Bill. I took it into an auto shop, and there was an exhaust leak under the hood, unrelated to the engine code. The mechanic wasn't certain what was causing the code, but they did notice the intake gasket was leaking (103k miles). So I need to replace the gaskets. Other than that, his only guess was the air flow meter and sensor being dirty could cause the code. So I'll take care of that when I attempt the gaskets.