So ever since I got my exhaust work done my car has been acting odd. First I'm thinking its the for but I'm not sure. On cold and warm starts it stumbles and stalls if I don't press on the gas to at least 1k rpm sometimes 2k rpm. Some times I get the p0420 code. My o2 sensor seems to move slowly and doesn't even reach 9mv according to my torque app. My iac is around 58 My maf use to be around 5.4 now its over 6 and goes up when it starts to stumble. Also when it does stumble I can hear the vacuum pulling close to 0 before it stalls. Please help.
