Can an UpPipe that has failed (i.e. 04' Catted stock uppipe) cause the vehicle to stutter and almost bog to stalling point. I know when my cat. converter failed and broke apart it started to clog airflow and would not allow acceleration and stalling points. Could this be something that is causing me to have stuttering , it doesnt happen all the time. I also had a cell come on once but then later it was gone, which was the ...hmm number escapes me but it was "Bank 1 to Rich", any ideas or suggestions are helpful.