Surprised no one has mentioned this yet but CHECK YOUR BATTERY! It may either be time for new battery or the connection between the battery cable and the battery terminal could be getting a bad connection. Corrosion on the negative terminals of our batteries is a fairly common problem and corrosion will often times lead to poor connection to the battery.

Definitely worth trying to at least look over the terminals for anything that might be causing a bad connection and if need be cleaning or simply removing and reinstalling the cables to the terminals.

Good luck!