After reading this there are probably a few things that need to be done
Since the driveability issues has never been fixed the two parts you have not addressed are the HES,
and the 02 sensor possibly damaged by the rusty pipe fitting episode.
That said the whoosh of air may be a loose spark plug or possibly stripped out threads causing the plug to come loose.
if not that then maybe the intake manifold has a leak and is letting intake air escape possibly in conjunction with the failing HES
I would also give the fuse relay panel a good going through maybe replace a running relay.
The grinding may be incidental to the running and the battery terminals may be loose,
or the wires that go to the starter are loose or dirty,
or a failing ignition push button.
This is what i would do in order
Remove starter and clean and install,
clean battery terminals.
Inspect the spark plugs for correct torque,
and possibly replace them with the autolites
Inspect the intake manifolds for leaks
Install a new airfilter
Replace the O2 sensor,
Replace the HES