2003 Cadillac Escalade engine problems

Engine Performance problem
2003 Cadillac Escalade V8 All Wheel Drive Automatic

car idles rough when you first start up. When you shift it into gear and try to go it hesitates and stalls. Seems like it gets worse as it warms up. Read the codes it read missfire in cylinder 2. Swaped out coil packs to test it and cked the spark plug. Plug was good and it tripped a multiple missfire. Replaced coils and cat convert. No luck the only other option was the egr valve could be clogged but my vehicle isnt equiped with one. Is there something that has to be reset when you change your plugs, coils, or wires. Oh is sounds like its not getting air or not enough fuel and the fuel pump is fine. Any sugestions thanks