My son has 92 F150 351w Std cab Short bed (single tank). Truck ran fine at low speed. Driving home, about 45 mph, it started sputtering. It has all new electrical components. checking fuel pressure, it is right at 30psi at idle.It goes up when removing vacuum line from regulator.When you rev the engine, the pressure goes up slightly but then drops to about 26 briefly as the rpms drop back down and then back to 30. Is it normal to briefly drop below 30? Im trying to figure out how to rig the gage so i can get the hood shut and see what it does driving. Maybe the fuel pump is failing when it gets hot?

 

Pressure should never drop below the idle speed measurement, the pump is suspect but change the fuel filter first if it hasn't be done recently.