96 nissan gxe problem help

[skyeyed]

i have a nissan sentra gxe 4 cylinder doing crazy things. First my battery light and brake warning light came on at the same time. Thought maybe altinator but kept running fine altinatored tested ok then three days later driveing down freeway at about 65 mph with ac on and all of a sudden my speepdometer drops to zero and my air bag warning light starts flashing. I turned off ac and light went out and speedo went back to 65 go about 10 more miles without ac on and it does it again at a stop light then start spitting and sputtering i nursed it home but help i am at a loss and this is my olny transo right now HELP ME PLEASE