When I first start up my car the idle is not consistent. It bounces from 500 to 1000rpms. It never fully goes away after it gets warm but its not as drastic of a "surge".

What could be causing this?

 

Any SES lights? Does it go away once you crack the throttle a bit? It could be quite a few things at this point because I assume this L05 is in a thirdgen and is therefore not stock so I have no idea what computer you are running or if you've tuned it at all. A bad tune could cause this. I had the problem and it was my TPS which had a dead spot at idle. Search for Testing TPS and start there. Is everything stock on the motor?

 

Had the same prob dude...My prob was the EGR valve....I blocked it off and my car has been running just fine....If you have emissions check you could replace it cheap..
Its also easy to check...Just unplug the vacuum line to the egr and plug it...start the car and see if it runs differant...if it does then you have your answer....Dave

 

All the previosly mentioned problems could cause your condition. Don't overlook two items as well. The Idle Air Control Valve, (IAC) which is basically a motor that adjusts the idle as a controlled vacuum leak. If the pintle ( the end of the motors vavle) gets carboned up it can fail to seal properly causing additional idle air past. This leads to the second item to check for, a vacuum leak. The ECM will step the IAC if a vacuum leak is present in an attempt to keep the idle RPM in spec. Many high mileage engines run every day with minor vacuum leaks that go undetected because the ECM has enough lattitude to compensate. When the leak gets too bad the idle becomes erratic. Check your IAC for carbon and/or use your favorite (safe) method for locating a leak. Hope this helps.