I've got a 1997 with a 4.6l engine throwing P0171 and a P0174 codes. I couldn't find any leaks by spraying carb cleaner, and there felt like pretty good vacuum when I put a thumb over a vacuum line ( it left the circle imprint on my thumb pretty quickly).
I also cleaned the MAF sensor with MAF sensor cleaner with no change.

I put on a code reader and checked the short term and long term fuel trims at 800 rpm and 1600 rpm and then close to 2500 rpm.

Bank 2 is about 10-15% lower than Bank 1 in all rpm ranges.

warmed up idle is about 20 (b1) and 16 (b2) combined st and lt
1500 rpms is about 20 and 17 combined
2500 rpms is about 28 and 25 combined.

So the overall trim correction gets worse as rpms increase. The only thing I can think of now is a clogged fuel filter or a fuel pump that is going bad.

I would appreciate any help at all!

 

Have you checked the PCV elbow behind the intake?

 

If the fuel trim gets worse at higher rpm, it's probably not a vacuum leak causing the issue.

 

I think my pcv hose elbows are good, and I am not sure, but wouldn't I be throwing one or the other codes but not both with a torn pcv hose?

 

The PCV elbow would throw lean both banks. You have to reach down behind the intake to feel it, if it's spongy or you actually feel a crack it's shot.

Check your fuel pressure with a gauge on the Schrader valve on the fuel rail. If the fuel filter hasn't been changed in 30k, replace it.

 

Wrong thread

 

Power brake booster, spray some starting fluid up behind dash where brake pedal rod goes into booster.

 

Looking at this, you have removed the cats, and are wondering why your vehicle is having lean conditions? It's because the computer isn't getting proper feedback

obd2 isn't the same as a carbed 302 from 1969....