Still chasing lean fuel trim codes. With no pressure on gas pedal, how much is throttle plate open? I was cleaning deposits off and noticed I can push plate down a few degrees to fully close it. Wondering if it is open at idle too much as only have high fuel trim numbers at idle.

 

If too open it would raise revs but not trims.

If you have +ve trims at idle and they drop if you rev (about 2500) then you have an air leak.

 

You're right, it's internal to air going through the MAF.
Fuel trim fine at anything but idle. Pulling 18 in Hg at idle so not a big leak. When removed intake manifold to replace thermostat tower, I didn't change manifold gaskets. Just ordered new gaskets and will see if that fixes. That may not be the issue because lean codes showed up a significant time after replaced thermostate tower.

 

Keep pumping that hot, oily air in there...