Someone Help Me Please!!!!

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?

Did you test the starter? Was it turning over at least?

tested the starter to. starter is good

The altenator is probably dead. You say you tested it but the symptoms are a dead alt.

HOW did you test the alternator, battery, adn starter?

AutoZone tests each of those parts for free. only catch is you have to remove the parts and bring em to the store.

i tested them i beleive twice one with a voltage meter battery and altenator and i tested the altenator again i started the car and took the negitive terminal off the battery and the car was still running. on my battery gauge my battery isnt reading between 12 and 16 volts but the battery is new.