[TJ]

Do this first. Check all the cables to the battery, and ground cables to the body and motor. Make sure all are clean and tight. if you have an old braided ground cable that shows signs of corrosion get a new proper sized ground cable. Next check the age of your battery. Optima's don't last forever. Also check the starter switch and cable. The problem could be somewhere in the charging system and you may be trying to run on a weak battery that is not being charged.