420A obdII wiring and cel issues

[josh_effin_tyre]

I bought a 99 eclipse rs for my wife in 2011. I noticed the obdII port wouldn't power a code reader, no big deal it had not thrown a cel so no worries. However about 3 weeks later it did but still ran fine so I haven't looked into it. After driving it for a couple years I noticed small thing but at that point I didn't care, it's been almost 4 years and now I'm curious about it. It had 160,000 miles when I bought it and is now over 245,000. Now I'm ready to remedy the problem, my question is since the 16 plug, obdII power supply isn't producing power, can I just run a wire from the battery or would it be better to use a fused accessory? The symptoms include a cel being on for months then going out randomly for weeks b4 coming back, the engine being peppy only when it wants to which is strange because one day it acts like it's stuck in a tar pit and the next day with the same weather conditions it will run like a raped date. Also I noticed a severe soot deposit inside the tip of the muffler, is it running rich? It doesn't use oil. My 420a has a front bumper exit cai, msd coilpack, and header, and sorry it's such a long post

 

[josh_effin_tyre]

Please everyone, don't all jump in at once