mojodet

i'm sure you guys are used to newbies like me so here goes. I bought an 03 gt and have little knowledge of cars but have always wanted one. What I bought ended up being modded with 02 sensors unplugged etc. after reading numerous posts in this forum I realized my car was prolly used at the track exclusively . I plugged the sensors back in and now I smell fuel like it is way to rich. I pulled a code that said rich fuel in bank 2. a mechanic told me it has stage 2 cams, performance intake and throttle body, ignition coils, lowered suspension, bigger sway bars(whatever that is), b&m shifter, 40lb injectors, long tube headers(sounds like a beast), and has everything installed to run nitrous just not hooked up. he said it may need tuned. it came with something called an sct flash tuner and he said he tuned it but stills smells rich to me, my question is can this car be made to be an every day driver without spending a fortune and how do I know if the tuner is right for the car without knowing what it is programmed for and if I get it dynod and tuned can I use this tuner or do I have to buy another one and do I have to tell them what mods it has when they tune it because i'm really not sure. a lot of questions I know but any advice will be greatly appreciated cause i'm lost right now.