First just wanted to say whats up? Im new, so yeah. Anyways Im not sure where to post this but here ya go. When im driving my car and come to a stop it starts surging, rpms drop to about 300 then pick back up. Also when im just sitting only after it has warmed up it will also surge. I have the cats cut off but no code yet. Do you think that could be the problem, if not what could it be?

 

My car does it when in drive before it warms up good. It will also do if after warmed up but only when I first stop, it levels out to 500 rpm fairly quickly. Its real noticable with the A/C on. The surge is max from ~300 rpm to ~700 rpm. Idle is 500 rpm.

I think mine is from the converter, a Yank ST3500. After its install is when it became common. First started after the Loudmouth catback went on though.

 

I have basicaly the same exhaust set up bu twith no cats. Do you think that could be the problem? O2 Sensors? I have an air/fuel gauge if its right then i think it could be running lean.

 

You may try cleaning your throttle body.If the idle passage is dirty than it can't control idle
Alan

 

True, also check your PCV valve. Mine has settled a lot. What I did: fuel system cleaning (kind where you let the cleaner be siped through a vacum source), new PCV valve (old one had oil in it) and catch can, cleaned TB, MAF, IAT, and reset PCM. My surging is greatly reduced now. Of course, it is winter so I don't use the A/C. That's when mine did it the worse.

 

I'm having this problem and I believe it is 02 sensor related in my case. I'm getting codes for bank 1 sensor 1. I am dreading going out in the garage and trying to fix this as I know I will have to drop the y pipe and it is about 10* outiside right now.

 

could also be a bad battery and or Alt