Shuts down while driving

I am not a mechanic, my car is not showing any codes. I recently added an aftermarket radio. There is a recall on my vehicle; the key comes out the ignition while the transmission is in drive. I need to have it fixed. I have noticed that every once in awhile my car just shuts down while driving. At first I thought maybe a vapor lock as it only seems to do it after the temperature gauge reads halfway between 1/4 and 1/2. It will refuse to start up for ten to fifteen minutes at times unless I remove the key unlock the door open it and lock it with the remote. I then have to wait a minute or three then unlock open shut the door and then start it. What is wrong with it? Please someone help? I am getting to know the local police dept very well as I am causing jams on the freeway on a daily bases now and it is not even summer yet. I love the car it is fantastic other than that. Thank you for your time and patience.