Hey all - I am new to the scene and the forum. I have an 07 Mazda 2.3l with an AEM Intake and a Magnaflow catback exhaust. I am now experiencing a hesitation when I am on the highway and also when the car shifts from 2nd down to 1st. This is driving me nuts any ideas?

 

Is the intake / exhaust a new addition?
There could be a bad ground, I pulled a few off mine and found a hell of a lot more corrosion than expected, and that's common to cause hesitation issues.