I have an 02 3.8 mustang manual ..when i bought car he said if u drive every day its fine but if sets a few days it drains the battery..but today i drove to walmart inside for 15 minutes when i came back out it didnt have enough juice to start.windows stuff like that worked dine..i tried roll start and it would start.i got a jump and it started but after that my instrument panel nothing worked on it it and was running rough and trying to die..but when my instrument panel started working again.my engine started running fine..after i got going down the road the motor straightened out and ran like no problem..can someone please point me in the right direction to look for the problem?