This is kind of a long shot, but try this.

Every night when you park, loosen your fuel cap, and again in the morning before you go to start it, and see if any excessive pressure comes out/sucks in. If you fuel pump is old and getting weak (any gas coming out the weep holes on the bottom of the pump?), a clogged evap system might create just enough of a pressure problem to explain the symptoms. Maybe?

My Truck: 1987 XtraCab DLX 22R 4WD 5 Speed Manual
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"Speed has never killed anyone. Suddenly becoming stationary, that's what gets you." -Jeremy Clarkson