If the air is coming out of the throttle body, it pretty much has to be a problem with how the intake valves are sealing.
I would look into borrowing a leak down tester and seeing how bad it really is before going any further.
Actually, before I did that...... while I had the hose hooked up, I’d use a brass hammer and tap the intake valve a few times and see if it improves.
It could be as simple as some heavy carbon deposits on the valves, keeping them from properly seating.
I’d still do the leak down test afterward though.
This is great advice. I'll see if I can get my hands on a tester. I'll try tapping the valve. Not sure which is intake from exhaust though. I'm guessing the uppermost of the two? The thing that stumps me is that they are all showing the same symptoms.
I'm hoping that the slow manual manipulation of these things may have things out of line a bit and they will all vibrate into place and seal properly once the engine is run.
