That is a fair assumption harness tests ok and I traced my fuel pump relay with a tone and probe tool, I used some dielectric grease and reseated it a few times and the cut out is not consistent so...

replaced parts include

alternator, rebuilt tbi, fuel pumps, fuel pump relay, fuel pump actuator (dual tank), ingition coil, distributor cap/rotar, wire, plugs, maf, clean and polish grounds.
...

I have been replacing parts chasing an intermittent cutout in my 88 gmc dually. Im basically to the ecm and swapped a reman from autozone and put my chips in. Its acts like a 3 speed instead of a 4...

88 gmc dually TBI project... fuel,spark,air research