360 runs great one day and then poorly the next

JoeSBP said

more detail on "runs like crap"
Idle, cruise, WOT no load, WOT under load, does it every go from running well to abruptly running poorly, or does it only run poorly once it's started that way?

I would start by closely checking all your plug wires, to include resistance, then checking all your wiring.
make a list of your checks, then do the same checks with the engine fully heated up.
And a part being new pretty much means nothing. Every part works correctly, right up until the point it no longer does.

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When fired up it would run perfectly. The next time, it would run like it loaded up push heavy exhaust. This is at idle, couldn't take it down the street too far without fear of dying. Other days it would run great, no issues even under load driving it around.

So, it all depends on the day after it starts up. The weather is not a factor because it only sees nice weather on the road.

Put the original parts back in and still would run just fine and then wouldn't.

That's why the engine compartment wiring was replaced, thinking that was causing the issues. Again, works great and then not.