Lt1 Left bank running rich

Hey guys! I have a '69 Camaro I put a LT1 out of a '96 caprice in it with a T-56 tranny. The problem I am having is the left bank is running rich. Plugs are black. The right side is fine (plugs) It idles fine and drives fine until it warms up. Then starts to hesitate and stumble while driving. It has new o2 sensors, headers, 58mm TB and a mild cam. any ideas? Thanks!! -Tony

Hey guys, It ended up I had the O2 sensors hooked up backwards. I switched them and it's running great! Thanks!:runaround: