One of my company's 2006 Silverados with the 4.8L V8 is throwing the code for both banks of cylinders running lean. There's a leak somewhere in the brake booster. If I disconnect the vacuum line to the booster, plug it, clear the code and restart/run the motor, the code stays off.

The check valve and hose are both in good condition and don't leak. The grommet is clean and sealing well.

Anyone else have trouble with something like this? Seems young for this to be busted already.

Of course, it's out of warranty now due to mileage (we use this truck a lot).

I don't want to drop $120.00 on a new brake booster if that's not going to fix it.