i have mac headers and today i installed a mac offroad pipe and o2 simulators after the install, fired the car up and the car hesitates and car wants to die, no codes, no service light, car ran fine before, just after i installed the off road pipe car runs like crap, drove it and it dies, check under the car and everything looks good, any ideas what can cause my car to run like crap after i installed my off road pipe? doesn't make sense, any ideas?

 

Reset the computer. It has learned the motor with cats. It will need to learn it without cats, air flow has changed. Resetting will make it learn faster.