2005 5.3l crank squeal

[SLCHOE]

Truck runs fine except for chasing a p0171 74 codes that should having nothing to do with it....I have tried all sorts of vacuum leak tests.....and they aren't related timing wise.

Good oil pressure. ..clean oil, clean tyranny fluid..

Aha! You may think they are unrelated but it sounds to me like you have a vacuum leak at the rear of the intake manifold (gaskets). This makes sense since there is high vacuum at idle and low rpms since the throttle plate is closed. Open up the throttle plate and manifold vacuum decreases (no squeak). At times a vacuum leak from the intake gaskets can make a squeaking noise like you are describing. This is what I'm thinking is your issue.

Get the engine running after sitting overnight so the engine is cold. Take a bottle of water and pour water around the perimiter of the intake manifold. Go all the way around listening for the squeak to go away and you should hear a wet sucking sound. Also the engine should drop rpms.

(all useful info but skip to 7:00 to get to the water test)