Without seeing how your car reacts at 5k rpm's, it's hard to say if it's maintenance issues, or tuning issues. Does the car just fall on it's face at 5k? I guess my question is, why do you think that it isn't pulling like it should? What are you comparing it to?
As for tuning, go to
www.sctflash.com and enter your zip code on the right side, and how far you are willing to travel. It will pull up a list of SCT dealers, some of which will have websites and dyno shops. Get ahold of them and see if they are able to tune your vehicle. A quality dyno shop won't request that you purchase an Xcal2, unless you need more than one tune. If you plan to stay N/A, and are done with your mods, then just get one dyno tune and be finished. SCT dealers will have the software needed, and be able to tune your car without the Xcal2.
Mark