Ok, I'm sure this has been asked before, but I am going to ask again. I just replaced the EGR and O2 sensor but I am still getting the 181 and 334 codes. Along with the check engine light comes a drop in power and a 'bucking' as I let off on the throttle but not while I am accelerating. Any suggestions on what to start looking for and how to go about diagnosing this problem on my own. Any help would be most appreciated. Thank you!