Drew, with the Roadster I had some issues like this , especially when I went to the injection, go spend some money cheap guy, and get a UNI Filter...It made no change in power , but with straightening out the air flow made a world of difference...actually picked up a little MPH, vs air pans etc...
Same one that Ken and Tim run, check them out...
http://www.unifilter.com/online%20ca...utomotive.html