I had already checked for full throttle, made sure the fuel shut off valve was not partially engaged.

I had read about the possibility of the fuel tank having issues, going to consider dropping the tank but I think according to the manual, they want you to test fuel line vacuum at the lift pump, or fuel pressure at the lift pump outlet. Need to gather the fittings for that.
Not sure what is faster, dropping the tank or checking vacuum and pressure.

Maybe since this truck is 27 years old it makes sense to drop the tank and clean it out and check for condition.

Thanks for the info.