misfiring and running rich and hard to start?

I have a 1996 Chevy suburban k1500 I hooked the car up two a scan tool and got a reading of bank 1 and 2 are rich and cylinders 1and 3 are constantly misfiring while at idle but only at idle so I replaced the plugs wires and cap and rotor but I still have a hard time starting it and the check engine light is still on so I checked the compression and its all consistently 180lbs because I figured where cylinders 1 and 3 are next to each other than my head gasket was gone but where the compression is all the same I am completely out of thoughts any ideas[/code]