This winter I installed a new alternator and battery on my mustang. It would start and run just fine. Took it out for a drive the first time the other day and it would almost die going over bumps. Then on my way back home it died on me. The car turns over but doesn't start until battery is charged above 12 volts. I tested the battery while car was running and it ran a little below 12 volts. I don't understand why its doing this because it has a brand new alternator and battery. I lost my keys a few weeks ago and had to get a new ignition lock cylinder but I messed up the housing so bad I had to just get a whole new column with the key. Could there be an issue with that? Or am I dealing with something else?