1989 trooper just died

If you don't know for sure, you will need to figure out if it is a no spark or a no fuel pressure issue to proceed.
If it is a no spark problem, check the ASD relay and the coil for voltage and ground signal.

sounds like cool gets hot and quits or fuel pump weak

when car dies check for spark if you have no spark check the igniter and coil as well as spark plugs cap and rotor

may be a fuse or coil check for spark had simaler prob with a jeep ended up being a fuse for somthing completly differend but they run in same sercut

It won't die when pulling the relay because it has another power path to the fuel pump through the oil pressure switch . Fuel Pump Electrical Circuits Description and Operation watch this video on fuel pump control , shows chrysler first , ford ,then gm . wait for gm an he explains the oil pressure switch . Plus when it won't start ,don't guess or theorize ! Test what's missing ? check for spark , no spark check ignition system , coil's , ignition module , crank sensor etc... has spark ,do a fuel pressure test etc... don't think computer , when it won't start does the check engine light come on with the key on run not start . If light is lit ,nothing wrong with the cumputer . If want to fix cars you really should take some automotive classes . Test don't guess .Watch some other videos crank no start videos etc...

electrical fault all day

fuel pump,or bad ecm, or bad coil or coil wire

Sounds like a fuel problem, Bad fuel pump relay of actual fuel pump check relay first may be working intermittently.( Replace relay first before going to pump). Good luck thanks for using FIX YA

No not the magnet, but the coil of wire that it inductes into when it passes, this tells the ignition module to fire the coil. Yes these fail all the time, they are usually ok until they get hot then then go "open"

have someone kick at the gas tank while you are turning key if it starts it is fuel pump