Pontiac Firebird Problem?

[z9francisco]

I have a 1990 Pontiac Firebird Problem. When I am driving the car works fine but when i slow down the battery gage moves up and down and it goes lower than 13v and then the car turns off. The car will turn on right away. I went to Autozone and they said that everything is fine (alternator and battery) what should i do? What could be wrong? I just replaced the spark plug cables and the spark plugs. Can someone please tell me what might be wrong.

 

[Nomadd]

Autozone isn't a repair center. They do things as a favor but aren't mechanics and shouldn't be relied on to troubleshoot your car.
The battery gauge might be going down because the engine is going too slow, not the other way around. You didn't say if the problem existed before you replaced the sparkplugs and wires. There are many things that can make an engine idle poorly at idle. The battery voltage reading low could be the engine going too slow to run the alternator or a bad ground between the block and chassis.

 

[melsg5]

when is the last time you replaced air and fuel filter?