My 2001 Silverado 1500 with the 4.8 liter is giving me a P0300 random misfire code. I am at 170K miles on the vehicle and the code comes up when only when the vehicle has been at a constant idle or speed for 5 minutes or so. So if I leave it idle for 5 minutes the truck will start to rough idle and hesitate and if I give it some gas, it smooths out and runs fine for another 5 minutes or so and then the issue repeats. The same is true if I am driving on the highway. If i put on the cruise control after the 5 minutes or so the saem thing happens. Speed up and it goes away. So far I replaced the plugs, wires and coil packs. I tested the EGR and found that the voltage being returned as low so I replaced that as well. Last thing I did was replace the fuel regulator. All of this had no major effect on the issue although the truck runs great when it runs smoothly and the gas mileage has definitely gone up so it was not wasted effort. I do not believe it is the fuel pump since I replaced the pump and all the fuel lines from the tank to the fuel rail about two months ago when the factory original pump gave out. I replaced all the lines since each part of the line I touched just crumbled and I figured that it was just cheaper to get the entire set from the dealer rather than piecing in sections that I broke trying to get them off. The other think that is funny is that when the truck is experiencing the issue, the Check Engine light flashes for about 15 seconds and then goes off. The only way I know the code that was put out was to use a code reader and it shows as a pending code. So does anyone have any ideas what else to check? I am currently on the road and the plan is to check ohms on the fuel injectors to see if any one of them is out of wack with the others. I am out of thoughts as to what else to do if it is not the injectors.