I replaced the fuel filter and the IAC Valve (Idle Air Controller Valve) No improvement...

My 2001 Chevy Silverado 1500, 5.3 vortec, is misfiring on multiple cylinders while idling in drive. When I stop at a red light, some times, the misfiring is so bad that it noticeably shakes the whole truck like I'm in the middle of an earthquake. The hotter the engine temp, the worse it is. I bought ...