1996 Ranger v-6 fuel pump relay
 

My Ranger has started just dying while going down the road. When this happens I’ve found out that all I have to do I switch out the fuel pump relay with EEC control module relay and it will crank right up and go good for a while and then it does it again. I swap the two relays back and it’s fixed again for awhile longer. Any ideas what might cause this.
thanks in advance.

How about this?
Do you get the same result if you just remove the fuel pump relay and reinstall it in the same place without switching them?
Because the 2 relays are identical , it might be a good idea to purchase one new one.
Also, one of them could be on it's way onto retirement and either on could provide the same result in their normal position.
There are other things each relay controls , but when the engine decides to quit, do you lose any other functions , does the check engine light come on at any time?