I have an 02 silverado 5.3 and I keep getting a random misfire code on all 4 of my pass side of my engine. I have changed the spark plugs and even changed the fuel pump because that went out like 500 miles ago lol but still nothing. The check engine light always flashes around 2k-2500 rpm and then stays on untill I shut the truck down and start it back up. I have also noticed that i lose alot of power up top and often when it goes into final gear it just kind of dogs out. I was told its more than likely my intake manifold gasket, but I just wanted more opinions before I start replacing anything.