Oil psi problem when starting truck

The oil pump filter screen maybe partially clogged can try flushing motor with an engine flush.

So you notice no knocking (bearings) or ticking from the lifters? If not, there is a fine screen type basket under the oil pressure sending unit that has to be fished out and cleaned, as it gets gummed up blocking a true oil pressure reading. Replace the oil sending unit since it is out, your there anyway.