I have been battling an issue with my 12 year old car that I received as a gift. It started out as a very minor issue. They replaced the manufacturers radio with an aftermarket JVC radio years ago. It had the slight annoyance of dropping the radio signal when my phone charger was plugged in. I let it go but lately the electrical problems have gotten worse. It started with a very rough idle when stopped at a sign/light. I didn’t know what the problem was but there was an issue with the Catalytic Converter so we had the whole exhaust replaced with aftermarket parts thinking that was the issue. I kept saying I thought the problem was electrical but other solutions were attempted such as oxygen sensor, replacing an air intake hose, a idle sensor, and relearning the idle. None of this has helped. The problem increased once my husband had an HD radio installed in the car. Now I cannot drive with the lights or radio on - it kills the car dead. The battery was replaced in the last six months and they tested the alternator- he was getting 14 volts while running.
Any ideas on what else we can try? Is it really worth getting wiring fixed on a 12 year old car that has seen better days??