[Cabnchassis]

6 or 7 common things cause these trucks to have air/fuel issues, I would suggest going through them first, but don't replace anything you can't verify to be the issue. If you're factory parts still function correctly, they're better quality than what's available to replace them.

WIth the engine running take a can of starting fluid, and spray around the intake manifold, throttle body gasket, and anything else that carries vacuum through the system.

Verify that the engine is reaching operating temperature (check the book on what it should be for your engine configuration, but anything over 180 should satisfy the PCM)

If the PCM gets information it doesn't like, it will overfuel the engine to keep operating temperature as low as possible. It will also change operating conditions based on the data it receives, making it hard to pin down symptoms at times.

Change the two TPS sensors if need be, they're difficult to test, and some of the cheapest parts in this adventure.

If you start spend to spend more money, stop, and use a multimeter and make sure all the circuits on the fuel/air distribution systems are functioning as advertised.

Common Cutter Outters
-MAP Failure
-IAC Dirty/Failed
-Throttle Body Gaskets
-Intake Manifold Gasket (Sometimes crosses over internally, difficult to diagnose in that case)
-PCV
-EGR Leaking/Clogged
-Vacuum Leaks of any sort
-That something else you should check that I can't remember right now....

These trucks had two consistent/common failures...The wiring seems to be biodegradable in many of them, and at some point all of them will have issues with 'cutting out' due to one or many of the factors I mentioned above.