i would start with a basic - the battery. check to see if the connections are tight and not fowled with deposits. if you can check the water  ( if it is not a sealed unit ) after that you have many different options. if you are not mech. inclined i would not go any further. you dont have a person to check it out im guessing so you might take it to your local station and ask them to just trace it out for you. tell them what happens and make it clear that you do not want them to fix at that time. stations that you deal with will gladly do this for a nominal fee or no charge ( sometimes ) other than me looking under the hood there is too much that could cause this problem to pin point here and now. it could be electrical-fuel-computer- or something like the ignition switch. sorry i couldnt help - good luck