[BR3W CITY]

This is your first post, and your chasing all sorts of different things. Take a breath for a second, and lets actually pinpoint and identify whats going on.

When you searched and found those items to check, did you then search those things to find out what actually needed to be done? Might seem overly simplified when I state it like that, but following up on that search (with terms like "checking fuel pressure", or "finding vacuum leaks") would have already got you to some of the info you need.
Don't get me wrong, we're happy to help...but with so much info being tossed in one post, you gotta follow up on some of your own leads/research.

Do not spray water on your intake gaskets, you're thinking of the soapy water on air leaks thing for tires etc.

Carb cleaner/starting fluid/ether can be used on the intake sparingly. An intake leak is vacuum, so it will suck in the combustible fluid and cause a small surge in idle.

Pull the vac line off of the FPR and see if it changes. If not, or you can't tell, put the gauge on it. Less than 55-60 (ideal 58) will not work unless its an flex fuel truck.

If its DBC, make sure the throttle body isn't caked with crap, and that it opens and closes normally with getting hung up. Also make sure no ones' drilled out the little air bleed hole.

Here's how a lean code runs rich; you need to consider the way the system feedback cycle works.
A vacuum leak causes air to enter the system AFTER both the MAF and the throttle body. That air is unmetered and not the result of the TPS change, so the computer isn't expecting it.
That "extra" air mixes with the existing fuel charge (what the computer is expecting for fuel), resulting in a leaner mixture than is called for in the VE tables.
The 02's see the lean mix and try to fatten the burn with extra fuel.
Back up on the intake, the MAF and TPS, STILL don't see the change because the air is entering after them in the system.
System now is running with the extra fuel to try and compensate for the unmeasured air, but it doesn't have said measurments, so it ballparks over-rich to comp.
Now you have too much fuel in the mixture, but sensors still seeing the mixture as lean because of the air. Hence, black pipes, but lean codes.

Its also worth checking that you don't have one or more massive exhaust leaks before the 02's.