hello all! i'm so happy to find a site dedicated to pontiac'*! anyway, i have a 2002 pontiac bonneville sle and for some reason it has a rough idle. sometimes it seems like the car wants to die but it dont, just feels like it. i have already changed out my plugs and wires myself which has made no change. i am not noticing the idle gage moving up and down but i am really concerned and would like to fix the issue without going to some shop and having them try to lie and take all my money. you know how that is! lol. anyway, if anyone has any suggestions or may know what it is please let me know, thank you so much!!!!

Do you notice the problem only at idle?
What if any other maintenance has been done to the car? (fuel filter, TB cleaning, etc)

With plugs and wires out of the way first thoughts on it are vacuum, dirty throttle body or intake. Could also be one coil tower post is corroded. Seen that a bunch of times.

What area are you located near? Sometimes it helps to have other folks take a look and brainstorm as well. Possible toss it on a scanner and maybe something is noticed while scanning.

no other maintenance has been done. and yes i only notice it on idle. i do know that it doesnt have the power that is should. and sometimes it doesnt do it at all. the service engine light is on and i took it to auto zone for their free diagnostic test but i get conflicting results. one guy said multiple misfires, one guy gave me a code for an emission sensor. so i figure i would try and research the issue on my own. i will say now thinking about it if i get to high speeds or do passing i do notice a studder or shall i say i can feel a "miss" in the motor.

oh and i apologize, i am in Bryan Texas

Welcome aboard!!!
You might want to consider an O2 sensor. That may be giving you a misfire and your check engine light. Another possibility is a bad catylitic converter. If it'* plugged, even partially, that would give you a number of issues similar to what you're experiencing.

is there a way that i can check my converter myself?? and is it hard to replace the o2 sensor? meaning can i do it myself

I'd take Purple'* advise and get someone to do a full diagnostic on the vehicle and get some documentation as to what is going on. An O2 is fairly easy. There is a full write up and pics listed in the Maintenance section by a gentleman by the name of Dan Thurs. It'* very thorough and would help walk you through that project.

The converter swap would have to be done by a shop or at least someone with some quality welding experience.

This is the link to the O2 swap.

https://www.gmforum.com/t278913/

I answered this in her other thread. Let'* please cover this issue in that thread and keep this for introductions.

https://www.gmforum.com/t279691/