I have a '97 GT with a 5spd tranny. When I first start up my car, whether its cold or hot, it will hesitate really badly. I'll start to go I'll keep pushing down the gas, but the revs won't climb at all until i hit WOT, then it goes. Sometimes it happens if i sit there, rev and then it comes down and tries to stall, but never does. When it is happening, it sounds like the engine isn't firing. Once i rev for a minute it will go away and run fine. It has been doing this ever since I got my new exhaust on, header, hi-flow cat, muffler.
At first it was only giving a p1133 code so i replaced the o2 sensor. Now it is quicker, but giving me two codes, but no lights. My codes are:
P0335 CKP Sensor A Circuit Performance
P0342 Camshaft Position Sensor Circuit Low Input

Any suggestions on what I should do?