Pickup all of a sudden stalls, plenty of fuel and no air obstructions
Fuel and air are only 2 out of 3 things you need in order to keep a vehicle running (technically). Air, fuel and SPARK. How old are your spark plugs? Are they fouled? Does this vehicle encompass GM's spider injection system? While these may not be the exact answers, based on your description they are a good starting point.
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