99 Tahoe 5.7 vortex P0300 code HELP

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Is your warm engine idle 800 rpm? 30° C is not quite 90°, so the idle should come down after being fully warmed up.

The higher idle in your readings will affect the MAF reading. The MAF may be over-reporting the air that is coming in, but the engine needs to be at operating temp and at a good idle to be able to tell. At warm (correct) idle the MAF reading should be very close (in g/s) to the engine displacement in liters.

Can you get it warmed up and show us the ECT, MAF, and idle speed then?

I don't think that speaks at all to what seems to be a lean fuel condition on what looks like Bank 1 (?), but I don't understand where all the different short term fuel trim readings are coming from. There should be one reading for Bank 1 and another for Bank 2. Where are all of these O2 sensors?
 

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