Hard starts when warm! Please help!

[dcochran3]

Hey there guys, I'm having some trouble with my 2000 Silverado starting hard when it's warm and been sitting for a little bit. It's a 5.3. I replaced the Fuel Pump with a Delphi FG0407 and a new fuel filter as well. I had put a new fuel pressure regulator on it, but it didn't make a difference, so I put the old one back on. Doesn't shoot gas out the vacuum line either. I also cleaned the injectors and injector o rings,  put new NGK Iridium plugs and new wires on it too. I cleaned my MAP sensor and tested it, it is functioning correctly. I also cleaned my throttle body. Put a new MAF sensor on it a little while back, have cleaned it recently. Cleaned the air filter a little while back.Cleaned my idle air control valve. Put a new Engine Coolant Temperature Sensor on it as well. Does anybody have any advice for me? If it's a cold start, it starts right up. Runs amazing. No problems whatsoever besides the warm starting. I just don't know where to go from here. Any advice is appreciated. Thanks! 

[LS1maroZ28]

Have you checked your fuel pressure??

[dcochran3]

Yeah, it was low-around 40 when running before I switched the pump, now it's up where it needs to be.

[karlmg]

Try cleaning the idle air control valve if it is dirty.