96 gmc

I have a 96 GMC 1 ton with a 454 in it my problem is after my truck gets warm and I shut it off and go to start it again it just cranks and cranks and then it will finally start after some cranking the fuel pump in the truck is good it has a new fuel filter and a new fuel pump relay so I am looking for any advice to help me get this figured out

If it was mine I would do a 3m fuel injector cleaning. (I guess I like throwing money at parts to say I did it.) Otherwise since it is a replicable situation take it to a good mechanic for an analysis.