I have a 99 silverado which was getting hard to start. I checked the regulator and found fuel in the vacuum line. I changed the regulator and now it starts fine if you let the fuel pump run for it's two seconds before engaging starter. Fuel pressure flucuates at 600 rpm wildly, and when turned off bleeds down quickly. Anyone with help on this 5.3 fuel pressure problem? The truck runs fine once started.