The 1st gen (and maybe early 2nd with the 6g72)
have a separate bypass valve on the bottom of the
TB- it's held on with 3(or 4) long screws.
I'll try to take a few pics next time I go to parts storage.

This was something I'd had trouble with for years-
the truck would just stall occasionally when warm.
Sometimes it'd be ok, others it would be a real pain.
I tried various workarounds that often worked... for a while.
So last winter I got frustrated and went over everything-
and this is what I'd found.

I remembered a bunch of us had the same problems,
so I hope it helps.

t