Walk around the rig when it's full hot and key off. A leaking spider/poppet injector will make it reek of fuel just minutes after shutdown. Also as other keen minds noted, suspect a clogged inline filter. And/or check fuel pressure at key-on, engine off... and how fast (If you have a pressure gage attached) it leaks down.
If it leaks down fast, suspect a poor check valve in fuel pump, these trucks eats them and fuel pumps and regulators like candy.
Remove upper intake and inspect. If you see gold colored washing, while everything has a good patina of oil... suspect fuel regulator and poppet Assy. leak... it can happen in the hoses leading away from the spider injector.
If you service any top end injection, or even suspect the tank sender? Still... just overhaul the whole system from sending unit, sock, inline filter, FPR and the spider injecting set. Only because a lot of it is simply plastic and Teflon that gets old and crunchy over X-years. A fix/upgrade anywhere along the line can stress and break aged components.
After I fixed mine from tail to nose? I could have welded the engine lid shut. I had a leaky Fuel Pressure Regulator, and a poppet tube. So I grabbed those up, an inline filter and a fuel sending module with new pump and sock. Never looked at it again in the decade after until the truck was totalled out from under me.
Edit: The ignition system on these are pretty robust. If the wires are old and cracked looking when you fold it over a finger, replace. If plugs are worn, replace. If the rotor button and/or cap look to be carbon traced or cracked, replace.
But the biggie is if it stinks like gas after a hot run and a few minutes after letting it rest. If you smell the hot, heavy stink of fuel, do a full fuel injection service. Follow with tried and true ignition tuneup. A full plug, wire, rotor and cap swap. Wait... you said 2002?
I'm thinking 1995. A hard start or several key-on-key-off cycles could get a weak spider/FPR to build up until it fired. A 2K2 is likely port fuel injected. No more spider. But much diagnostics are the same. You need a hair under 58psi for it to catch and fire from the FSM. No more cap and rotor either. Likely a plug near coil setup akin to LSx series engines. These are Tonka tough, yet a bad plug, coil pack or shorty ignitor wire can make them hard to start... or trigger misfire at high speed.
If not suffering from low compression, low fuel pressure and/or fuel pressure bleed; then start testing the actual full operating pressure of the system. Easily tested by removing the vacuum line from the FPR and letting it hit full operating pressure. (60 PSI @ Idle)
