Clean the MAF sensor and throttle body. About the vacuum leak, you can use carburator cleaner to find out the leak or have a mechanic do the smoke test. 

If you suspect a vacuum leak you want to observe the fuel trims at idle.

Then you want to hold the RPMs at around 2500 for a little bit and see if the positive fuel trims diminish.

If it's a vacuum leak they will.

In your case your STFT is positive 10% at idle. (both cylinder banks)

So, check the fuel trims at idle and high rpms.

Do the positive fuel trims diminish at high rpms? They probably do because the computer didn't move any of that positive STFT to LTFT.

There's 2 possibilities and you're entertaining them both. You've tried adding fuel injector cleaner thinking about clogged injectors, but clogged injectors would be clogged at lower rpms AND higher rpms. So the positive fuel trims would persist even at high rpms.

Also, unless you're brewing your own fuel, what are the odds that 2 injectors on opposite cylinder banks got clogged at the same time?

Also, think about it. If you had 1 clogged injector on each cylinder bank and the computer was adding 10% fuel on each cylinder bank to correct that, you'd be running real rich on the other 2 cylinders on each bank.

Fuel pressure of fuel pressure regulator? That would affect fuel trims at all rpms and the computer would have moved that to LTFT by now.

So you want to focus on stuff that would affect STFT on BOTH cylinder banks.

And you're doing that. You're  looking for "unmetered air" and you're considering a vacuum leak.

But there's other reasons "unmetered" air gets into the intake. 

A dirty/stuck open PCV valve or a damaged (leaking) PCV valve hose. 

An IAC (Idle Air Control) valve that's sticking open. 

Faulty MAF sensor (lying to the computer about the air intake)

And of course intake manifold gaskets or a leaking vacuum hose.

So as far as the MAF sensor is concerned you want to see around 1/gs per liter of engine displacement at idle.

You have a 3.5 Liter engine. So, with your scanner (Live Data), at idle it should show the MAF at around 3.5/gs

Also. you don't have to rely on your hearing when doing the Carb cleaner/Starting fluid test for vacuum leaks.

You have to be generous when spraying the flammable aerosol so the intake leak can suck it into the intake manifold.

So it goes without saying don't do it in the garage and have the garden hose within reach.

Connect your scanner and set it to Live Data. Then while spraying the carb cleaner around, look to see if the positive STFTs  diminish when you spray in a particular area.

It's hard to get enough carb cleaner all around the lower intake manifold gasket area and you really have to "aim and inundate" the area with it. 

But if you see the positive STFTs diminish, that's a good clue

You've nailed down an intake gasket leak and it's right in the area of cylinders 5 & 6 (where those pending misfire codes are referencing)

So you have a choice. You can smoke test it to confirm, like @yaser advised,  or just move ahead and replace the intake gaskets. (I'd smoke test it. You're going to be removing the vacuum lines to change the intake gaskets. Might as well identify any other vacuum leaks and address them at the same time)

https://www.youtube.com/watch?v=c9toNCNWf20