Are you sure it isn't the battery? I let my other car sit and it drains the battery after while. Three months is long time to sit. Hell i have to trickle charge it to maintain some sort of charge on it and the car is driven a few times a month to keep it flowing. Now the battery is low and i drive it for 30 min to juice it back up but eventually i'm gonna have to replace it. Trickle charge is your friend.....