i dont want to ask this to make you sound dumb but when you put the battery in did you make sure that both connections were 100% tight? mine was doing that and it turned out that the negative terminal would be tight but if you tried to twist it, it would spin a little causing the car not to get a good solid connection every start up. all i did was take off the connector, squeeze it together w/some vice grips and bolted it back on. havent had a problem since. hope this works for you!
