2008 Yukon 6.2 engine fuel trim positive high bank 1

Hi, I have actual readings:
Fuel trim max positive for bank 1 (Short term and long term)
O2 sensor reading full lean on bank 1 ( both sensor 1 and sensor 2 read lean, close to 0.1)
Rough idle even in open loop.
Strong unburn fuel smell.

Everything reads normal for bank 2

Should this lead more to intake gasket leak, injectors or other possibility?

Thanks for your help.

I also forgot to mention that I have no trouble code except P0300 that happen once. I see random misfire on bank one only.

Cylinders:
1: 216 misfires
3: 858 misfires
5: 52 misfires
7: 406 misfires

If I reset I keep getting misfires in similar proportion per cylinder. Any ideas?

Thanks.

Is the fuel trims maxed out at idle or under load? What are the trims at idle? Do the fuel trims get better under load? (3000 to 4000 RPM)

Fuel trims stay between 26 and 31 idle, 2500 or 4000 rpm. Both bank 1 o2 sensors reads 0,45 and dive to 0 once warmed up and stay at 0, no oscillations.

You may be dealing with an intake gasket leak. Smoke test it before it gets warmed up. Also, you can do the water test that Paul suggests.

Good idea for smoke test when engine is cold. I will probably order a smoke tester and try. I did water test with no results. Also listen for leak with rubber tube. Could not find any vacuum leak. Intake gasket seems also well seated and check intake bolts and they are torque according to specs. Not sure is it can help to find cause but MAP sensor readings are normal.

could be a bad intake gasket I'm leaning towards a stuck o2 sensor.  How does it run at WOT? See what you can do to force the sensor to read rich by spraying propane or brake clean into the intake while its running.  If you can't get any response force the sensor signal high with a test light or what ever you feel comfortable with and see how the computer responds.  

might want to also take compression of that bank to rule out mechanical problems . good luck

Thanks all for advices. I swapped o2 from one bank to other and still got same results. Engine doesn't run better cold or WOT. I am starting to believe that intake leak can be rule out as well because I cannot find leak or hear leak, engine not running better when hot or at higher rpm. What I troubles me is how much fuel is injected. I dropped the oil because it was starting to smell gas. I am not sure that a PCM could deliver that much fuel to try to compensate for an bad reading. I'm thinking of injectors. Can an injector that leak can cause a false lean reading? I may try to unplug one injector at the time and see if something happens with fuel trim.

I agree, it's maybe now time to look at compression. I see if I can do it this weekend