when the truck is experiancing the issue open the hood and feel how hot the ign coil is. Maybe it's getting weak?

Sounds like something is messed up that isn't used in open loop but used in closed loop after warmed up. If i am thinking right there are 2 temp sensors on the vehicle, one for gauge and one for the ECU. I would suspect the one for the ECU, someone with a scan tool with data display could easily test it. It's also possible to ohm them out with a multimeter

I believe that year only has one sensor for the computer and gauge.
Has fuel pressure ever been checked? Fuel filter ever been changed?
Any check engine codes?

you are correct, 98-up had only one so if the temp gauge works then that isn't it

I replaced the "engine coolant temp sensor" and fuel filter about a month ago. And No Codes pop up. No Engine light or nothing.

Fuel pressure was at 60psi when started up. The needle shot way past, then settled. 60psi is where it set, then would drop to about 55psi after about 10min of idle.

I know there is a 65psi minimum. But if the problem is the fuel pump, "would this be the cause of my symptoms"?

My 99 is doing the same thing. Can u please post up if you figure out what it is?

Correction with the PSI readings. They are as follows;

1st switch, eng off - jumps to 64psi then falls to 54psi
2nd switch, eng off - jumps to 64psi then falls to 54psi
start car - sits at 53-54psi
slow rev to 2000 rpm - holds steady @ 53-54 psi
punch pedal down real quick - jumps to 64psi
idle for 5min - vehicle runs steady at 53-54psi
turn off engine - spikes up to 64psi then falls to 57psi
engine off for 10min - falls down to 45psi

engine off for 10min - falls down to 45psi

Problem, needs to stay above 55 for ten minuets with key on engine off.
May not be only problem but it is a problem.

After explaining my symptoms to several outlets, the fuel pump has came up as "the issue", once or twice.

the thing that throws me off though, is that my truck doesn't sputter/die after idling too long. And the sluggish acceleration is only consistent after it is warmed up but disappears when it has been turned off for a while.

I don't like messing with fuel, so I'll take it to a local mechanic and have them do a Fuel Pressure test and Fuel Pump test professionally by themselves.

I pray that they find something less expensive ! lol

I've had the luxury of replacing several sensors with zero results. :icon_doh: (sarcasm implied)

i'll definitely post my results.

I just replaced my fuel pump last week and mine is still doing what yours is doing