So this is a buzz killer. 29,000 miles... been slightly off as of late in that when under hard acceleration it would initially fall on it's face then take off like a streak of ****. Under normal driving really no difference. Now when accelerating around 5000 rpm drops into RP. Exhaust note is different to me also. Pulled fuse 19 when purchased and now the note is not the same. Codes are p0300 p0301 p0303 p0305 p0307 p0171 p0174 p0420 and a c1109. So plugged cat is suspected but only a guess due to exhaust note changing. What do you all think? PVC, vacuum leak, any common items/hoses to this motor/car I should check first. Anybody had anything similar happen that might be of assistance? Thank you in advance for your time.

 

probably one of your cats is gone, mine went and the exhaust not changed. Maybe not, mine had them codes but went to restricted performance, and limp home mode, as you say "been slightly off as of late in that when under hard acceleration it would initially fall on it's face then take off like a streak of ****". Mine was the same.

 

If it's a catalytic convertor problem, time to look up FrickenJag. He makes custom high-flow cats for board members. You can learn more about his work in this thread.

 

Perfect... thanks.