Lately I've been having problems when I'm driving in that the engine will start to stutter/stumble, especially when it isn't warmed up. It seems to do it in the lower rpms and has only occured 3 times in the past 3 months (today being the third time). The engine doesn't throw the SES light when it happens and it hasn't done this before I installed my headers. Is it possible that my spark plugs or PCV can cause this (since I was planning on replacing both at 50k) or could it be related to the headers and the O2 sensors?

 

Check ALL your vaccuum lines. My '00 had a slow and small vaccum leak that eventually led to it's demise... after only 93k... and it would do something very similar to what you're describing...

Make sure you double/triple check all the connections you may have messed with then do the same thing for your vaccuum lines and such.

Mine, I believe, was actually from not torqueing the upper intake plenum all the way down...

 

What hoses should I pay attention to? To me it seems like the hose that hooks up from the driver side valve cover to the inlet tube is loose on the valve cover connection. Would this be the likely culprit?

 

Does the stuttering occur when you have the a/c turned on?.

 

No, all three times that it occured was w/ the AC off.

 

I would also like to hear a solution to this. I just put on longtubes and mine does the same thing. Only when its cold and below 2500k rpms. Once it warms up or is above 2500k is stops.

 

ALL of them.

While I don't think your pcv hose would cause this problem, I would recommend replacing it or getting some type of hose clamp on it...

 

OK, here's the update. I checked for vacuum leaks w/ the good old spray everything w/ carb cleaner trick and I have no leaks. I replaced the PCV valve as well and soak the MAF in some alcohol to clean it. Also checked the EGR valve and IAC and both are not clogged. The car still stutters. However, like I said before, it only does this when the engine is cold and once it warms up, it goes away. I'm thinking it's probably a sensor. So when the engine is cold, does it run in open loop? If so, what sensors are used to run the engine (specifically at idle and off idle since the engine is fine if I rev it to higher rpms)?