A friend of mine bought a bone stock L98 camaro that idles high. Is there a common thing that causes this or should I start looking for vaccumm leaks and what not. No check engine light or anything.

 

check the water temp sensor will make car idle high if not working

 

Definitely look for vacuum leaks. I don't know much about your L98 but on my TBI advancing the timing with out backing down the idle speed screw causes it to idle high.Put a timing light on it and see if it has been moved. If it has back it down some.