GMC 1994 1500 v6 4.3L

[Camzwhitegmc]

I have 1994 GMC 1500 V6 4.3L truck runs great full power, at random times while driving at high speed or low speed the truck engine light turns on and immediate loss of power, I lose about 20 miles per hour in speed this lasts maybe 20 minutes sometimes or as little as 2 minutes than the truck runs great after that this happens at times when it is cold or hot outside. I have replaced every sensor that the codes showed. Is this a fuel problem or spark problem? thanks for your help.

[2018GMC]

I would start by checking fuel pressure