Im having trouble with my 95 3000GT. i went to go start it up the other day and it wasnt starting. i got under the hood and tighten up the the terminals and nuttin happen. put my foot on the gas and the battery gauge went up.finally i get the car started. when i put my foot on the break my battery gauge goes down. ive tested the altenator and the battery and there both in good shape. what could this problem possibly be?