[DW SD]

Can you more accurately describe the symptoms when it loses power? Does it still stay running, but just at idle? will it rev up in neutral? Does it stumble, miss, shake, OR?

I was thinking possibly your fuel pressure regulator stuck open (reducing fuel pressure, though I've never actually experienced something like this).

I'd rule out the distributor belt, probably the fuel filter, neither are intermittent and would be most acute under load. The idle air controller seems unlikely. Even stuck wide open, it should have decent power at the top end. It just wouldn't drop to low idle.

Doug