Few problems with an 03 tahoe z71

[silky]

Hey guys/gals.

I am having a few problems with my tahoe and I need an emissions test so I need to take care of it.

1) CEL has been on for about 1 month. It comes on, I clear it, it comes back, I clear it and it comes back again. It comes back as different codes

The original 3 codes were Lean bank 1, Lean bank 2, and Random Misfire. The next time it was just Lean bank 1, Lean bank 2. The newest code is p0455, or Gross leak in te evap system...(lean bank 1, lean bank 2 is gone)...

Now, the truck has started to run funny since the cel came on. The gas mileage is down maybe a few % (based on how fast I fill and the avg/economy readout. Sometimes on cold starts tht truck vibrates. It's not a massive vibration but you can feel it. The plugs and wires are new so I figured the problem was a vacuum leak. I sprayed carb cleaner around the intake manifold and vacuum lines and what not and nothing changed. I did notice that the hose that goes from the MAS to that plastic thing that goes into the intake has no clamp where it meets that plastic thing....is this normal? I have some live stream feeds I would like your opinion on...

this is all at idle....

o2 sensors:

Bank 1 s1 = -2.5 to 0 % stft, and .075 to ~.800 volts

Bank 1 s2 = NA stft (weird?), and volts are pegged at .075 (cycles on when on the throttle, pegged at idle)

Bank 2 s1 = 5.4 to 2.3 % stft, and .08 to ~.800 volts

Bank 2 s2 = NA stft (weird again?), and volts pegged at .0730 (cycles on when on the throttle, pegged at idle)

MAP= 10.3 in/hg. Isn't this low? I know my stealth is getting about 19 at idle.

MAF= .658 lb/min

TPs= 10.9%


thanks guys, and any info would be appreciated.

John