Tracing a P0171 code

I am trying to find the cause of a P0171 code on my 1998 Grand Prix 3.8 GT. I took it to a mechanic and after charging me $80 told me he could not find it. He says a hose is loose at the intake and the whole intake has to be replaced. The hose comes from the brake reservoir. Can the part on the intake to which the hose is attached be replaced r repaired?

If your upper and lower intake manifold gaskets are original you may have to replace them and could be the source of your vacuum leak. As well as a dirty Mass air flow sensor.

If loose, just put a clamp on it.....