a few idling issues
 

So about a month ago I bought a 97 civic ex, for the price its surprisingly in pretty good shape. Without much knowledge of its past, I know that the timing belt, water pump and radiator was done. We replaced radiator hoses (seperate issue), spark plugs, cold air intake and repaired the entire exhaust. So the problem is it idles between 300-500 while in drive and now after replacing this stuff 900 in park. My other issue I noticed was the radio wiring. The yellow cable is cob jobbed from the battery, which I figured out while driving effects the idling. (having my phone plugged into the radio gives me a lower idle) I thought this was a separate issue at first. So if the fuses are fine, but the factory yellow wire doesn't give enough power to turn the radio on then what could be the issue? I hate the fact that the radio is powered straight from the battery. My next mission is to replace the spark plug wires and distrubter cap. Am I wrong for thinking these two problems could be linked? How do I fix the radio in order to give me a more accurate idle