Yes replace those relays if they did come up on a scan. This means at least one time they have failed. Yes just unplug them plug the new ones in. If either one of these fails it will not start. If it were mine I would replace them. So atleast you know it is not them.
If not them then the fuel pump is going to be the prob. You see what is confusing about the pump is that it intermittantly runs. But the pump is just a very small motor this motor has an armature just like any elec motor these armatures get flat spots on them. So it depends if when the motor shuts off where it stops if it stops on a flat spot it will not pump no start. Cycleing the key and beating on the tank will normally jar motor off flat spot and start pumping.
Cycleing the switch makes it hard to tell if you are actually bumping the pump motor or if you are bumping the two relays.
If it won't start and you do not hear the pump but hear the relays then beat on the tank vigorously and see if you can kick pump on.
Some of these years had a pump mounted right under the driver on the frame. Not sure if yours does. This was a high pressure pump the pump in the tank would pump fuel to the hp pump then to the injectors. When these pumps failed you would have idle no accell.
Tuesday, May 16th, 2017 AT 7:19 PM