I just fixed a problem on my 2007 Chevy Express 1500, V6 where it would stall. It turned out to be a broken wire leading to the ignition coil . Along the way I replaced the fuel pump and idle air control valve. I cleaned the MAF sensor and the throttle housing and I replaced the plugs and wires. Now it sets codes P0420 amd P0430. (catalytic converter bad) It never set these codes in the past. They appeared as soon as the prior problem was fixed.