Mainstream74

I have a 2002 Cey Tahoe 5.3 liter 4wd flex motor. Service Engine light on Po codes 171 & 174. Changed MAF sensor,Air Filter, Spark PLugs and Wires, BP gasoline anda bottle of heat. Still acts like it wants to shut off when idle, orwaiting ata light. If i hit itit takesoff like light but runs rough when I am sitting still. Can anyone help me out?