How do I fix my 2001 KIA Sportage with diagnostic Code P0171 Fuel system Lean Bank1?

The engine idles rough, throttle cable has a little stretch/droop, manifold gasket might be leaking it has oil stains around it. Had 60000 mile tune up currently has 80000 miles. Air cleaner is clean & PCV valve is new. MAF sensor is old origional. Idle speed control is origional. Coils & wires are origional.