[davepl]

I have only a gentle 30 degree in FRONT of the MAF, and I tried adding a 4-foot extension to it, which didn't change anything, so it's possible that the tube is the problem, but I don't think so.

I might try running the pipe backwards just to make 100% sure I don't have the MAF backwards, but its arrow is aligned with the direction of flow, so doubt that's it (unless the arrow points at the filter, but that'd be weird).

That picture is my car, BTW! So as you can guess this isn't for my truck but since the LS guys here know as much as the Camaro guys, I just asked here.

I connected vacuum to the engine (like a PCV but I plugged the intake ports on the valve covers) and it generates and holds a ton of vacuum in the crankcase, so I don't think I have a vacuum leak (it didn't change much). I also pulled off the vacuum hoses and plugged the brake booster line to rule out other leaks. Really feels like a vacuum leak, which is what the other guy thought too, but I can't find one.

Given that when you bring the revs up it reads OK, I think it has to be either a vacuum leak or a problem with the MAF's mounting. Can't find evidence of either though.