You've replaced a bunch of parts, apparently without doing any diagnosis whatsoever.
I get replacing the plugs, fuel filter and cleaning the throttle body. I might have also replaced the O2 sensor. All the rest of what's listed should have been checked/verified first, before replacement.
"Rich-smelling" exhaust is generally misfire; and it often leads to a failed catalytic converter. If the exhaust is restricted for any reason including a melted catalyst, and not all the cylinders are running, it's no surprise that the engine is down on power.
Verify all the rest of the usual "tune-up" items--cap, rotor, plug wires, ignition timing including the electronic timing advance, PCV, charcoal canister 'n' plumbing, etc.
Check fuel pressure, under load. Most fuel pressure testers have a button that can be pressed to "flow" fuel out of a plastic hose and into a drain pan, simulating high fuel demand.
Connect a scan tool, verify EVERY sensor and the computer outputs. Given the history of knock sensor problems and actual knocking, I'd be double-sure to check that entire system. Among other procedures, connect a timing light, and then tap a brass or small steel hammer against the iron of the cylinder head. (Tapping the intake manifold also works--but be aware that the intake manifold is aluminum. Don't whack it so hard that it cracks.) You should hear the idle drop and then recover, and see the timing retard and then recover, as the knock sensor/computer/wiring harness/ignition module pulls spark advance to "eliminate" the "knock".
Check for restricted exhaust.
Keep in mind that a 305/5.0 is a turd in stock tune.
About a thousand years ago, when I was pre-teen and teenaged, I knew a guy named Ron Hedden. But he'd have been on the other side of the country from you. Last I heard of him, he was in the San Fran area; and if you're related he'd probably be your grandfather...or great-grandfather; and I'm sure he's dead by now.