I have a 2000 silverado with a 5.3L engine that starts fine in the morning or when it has cooled down. The problem is that when the truck is restarted it takes about 10-15 seconds of cranking before it will start. When it does start it will generally sputter a little bit and then it runs perfectly again. Sometimes when it has to crank over especially long I will hit the accelerator and it will start a little quicker but sputters for a few seconds. There is no loss of power and the mileage is good. I changed the air filter and pcv valve, put some high quality injector cleaner through it and the problem persists...I am going to change the fuel filter, maybe the plugs too, but I don't think it is necessary because there is no problem after it runs for a minute or two. Could this be a EGR valve going bad or some sensor? Any advice would be greatly appreciated, thanks.