when the car is idling fine, the voltage is around 14 but when it drops below 900 rpm the volts go down to like 12 volts and then lower and the car dies. And when somethign is switched on the voltage drops sllightly . Is this a sign of a bad alternator. i searched too

 

that sounds like a problem with your voltage regulator, which is inside your alternator. It's job is to tell the alternator how many amps and volts respectively to put out depending upon the given load. Even at idle you don't have much demand, but your still charging no less than 13V. 12V at idle tells me your not charging.

Make sure all your connections on your battery and grounding points are clean and not corroding. Baking soda and water for that. Also if you have a voltage meter, using DC volts, check your voltage across all your positive and negative cables by placing your leads on both ends of the cable. A GOOD cable should read less than a volt. If you start reading more than that, it's time to replace cables or you have a poor conducting point. Corrosion doesn't conduct electricity very well. These aluminum factory cables tend to corrode from the inside out.

I suggest you read these two sites, they are VERY informative.
http://www.aaroncake.net/RX-7/grounding.htm
http://www.the12volt.com/installbay/...TID~73496~PN~1

also an easy way to test is to drive to the local auto parts store. most can check your alternator while the car is running. more food for though is you might have been slowly killing your battery, might. a good charge with a battery charger might be a good idea if your not running it.

 

Put a new ground wire from your negative battery terminal to one of the bolts on your strut tower. Also check to make sure your belts are not too loose.

 

Are you running racing beat dual alt pully?

 

no. yoohoo belt and stock pulley. It started to to this after i wired up a seperate harnes for my headlight motors, which run off of a relay. But even this added wiring that is hardly ever on made this happen. Maybe my ground is bad like u said.