Chevrolet Cruze Lights Malfunctioning

I have a Chevrolet Cruze and I'm having some problems with the horn, lock/unlock button, and rear left stop light. They seem to be acting up on their own, sometimes working and sometimes not. Every morning, I can't help but notice that the engine has a bit of a rough start when I turn on the car. Even after taking it to multiple places, I still haven't been able to figure out what's causing the problem. If anyone has the solution, please lend a hand!