Flashing cel at 5k at 3rd gear and above please help

[PAYBACK310]

Epfam....
Ok so i am having this issue that i noticed for a few days now......the other day i down shifted to 3rd to get passed some slow ass driver on the on ramp and when i hit 5k i felt a studder and the cel light flashed.. I then noticed that it did it on fourth gear as well but again only at 5k and above....does anyone have an idea of what this can be??? I recently cleaned my iac cus i had a cel for that and that code was removed but i need to change my primary o2 as well which is also a cel that is up...but this is new to me...never experienced it any ideas would be very much appreciated thanks

[AKEP]

like flickering? you have kpro?

[PAYBACK310]

the cel no it blinks the pull after 5k yeah flicker like it studders/pulls back/slow to get to6k...........No bro no kpro yet :(......any idea what it can be??? I recently cleaned my iac valve becasue it was at very low rom and stalling out...after that its good no more stalling....i do also need to replace my primary o2......could that be the cause??

[RotaryGreg]

flashing cel usually indicates a catalyst damaging misfire. check the code and see what you have. if its happened on more than one drive cycle it should have stored a code for whatever this is.

[AKEP]

replace the primary o2, without that the car runs pretty rich because its not adjusting fuel. the stock map is pretty fat. check your plugs too while your at it, probably need to replace them anyways.

[PAYBACK310]

Thanks alot for your help all...i have not had the chance to check the codes and i have been only on the stereets so i dotn have to passed the 5k i feel like i hurt my baby when i do it lol so after i check it out i will let y ou all know what it is or was..you know just in case you ever go through it..... And yes i think the o2 is really messed up becasue i put in normally 20 bucks on sunday and it last me till thur well i put it in and come friday night it was gone...so yeah most deff need to get that fixed asap