I'm trying to narrow down my problem, I think its either maf or o2, but if anyone thinks it might be something else, feel free to let me know, I really need to get this figured out.

Ok, what the car does is hesitate and die at least one time every time I start it cold. The RPM's jump around like crazy, it barely runs, won't accept fuel when I push the throttle, and just dies. After a couple times of that it starts fine.

Also, occasionally the car won't hold a steady idle, even after I've been driving a while and its completely warmed up.

Ideas?

Also...I do have a CEL from my high flow cat, if that makes any difference...

 

a good way to tell if the maf is malfunctioning is to get it idleing, and give it a good tap with the end of a screwdriver or something. If the car stumbles/dies then you've got a problem with it.

As for the O2 cell. The stock cats are high flow. So I doubt adding a high flow cat would actually cause a cell. Chances are you just have a dead/defective O2.

Your best bet is to actually pull the codes. I doubt your stumbling problem has anything to do with your O2.

 

I did read the code. I forget what the exact term was, but it was basically telling me that there is more air flowing through the cat.

 

Your MAF wont come fully into play until the car is at normal operating temps. A dirty MAF usually results in fuel trim related codes; rich, lean or I've even seen them cause random misfires. Over oiled, washable air filters do tend to junk up MAFs real quick. For cold start idle concerns, I'd try a thorough throttle body cleaning. Any dirt around the bore can keep the electronic throttle control from making the tiny changes in throttle position it needs to do to maintain cold RPM. TBW doesn't have idle air control.