01 Silverado staring trouble

I've got a 2001 Silverado 5.3 V8, just recently it has had intermitent starting problems. Sometimes it turns right over and other times it takes 10 or more seconds of cranking before it finally starts. When it hesitates to start it idles rough until I press the gas. And after it does start its is idling rougher than it used to. I've replaced the idle air control valve and that wasn't it. Maybe the fuel pressure regulator, or the crankshaft positioning sensor? Every thing else seems to be operating normally. I should probably add that the truck on has about 20,000 miles on it. Any replies will be greatly appreciated. I don't want to sink a bunch of money into parts and then still have to take it to the shop. But I figured I would do the things that I could do first.

Too many possiblities is it doing it only on cold start? Or warm start? Or at anytime.

The Cold start problem seems to be being diagnosed as possibly being a loss of fuel pressure. If it is warm you cuold check fuel pressure regulator. It should be on the fuel rail on driver side of engine ( not very large ) has a vacum line running to it pull vacum line if it has fuel in it its bad.

I agree with the fuel pressure loss. My thought is that the fuel pump may be bleeding down and allowing the line to lose pressure. The only was to be sure is to connect a fuel pressure guage to the line and see how it reacts.

my brother had the same problem with his 01 silverado he took it in and it was a dirty fuel injecter and the fuel pump was bad