i jus got a new alternator and battery put into my bonneville about a year ago and the battery gauge is still jumping back and forth from 14 to 12 when i coast real slow and when i idle. any ideas what it could be?

What year is your car?

i have a 96 SE

Take a look at this write up. https://www.gmforum.com/electrical-133/adding-sense-wire-your-alternator-278806/ It should help. But if your idle is low that can also effect the voltage. Also check on your belt to make sure it'* not worn or loose.

thanks man by the way u got the sickest bonnie i ever seen

Hope it works for you. And thanks for the complement.