1997 gmc pick up / engine runs fine but will periodically kill while driving. ?

When an engine dies it may have something to do with what the conditions are at that time, [temp, load on engine or rpm etc]. Unfortunately it can be a number of things..

Fuel pressure is a point to check, however I'd suspect the a fuel pump relay or power to it before considering a fuel filter.

If it dies suddenly, most likely it's an electrical issue. I'd suggest checking all the connections going to the ECM and those that pass through the firewall. Or it could be something as simple as a poor solder joint in the ECM or worn ignition switch. What most shops will do is swap out the ECM for a known good one.

Good Luck..

I would have the fuel pressure tested. You may need to replace fuel filter.