so yea im getting a new clutch setup for my 88 n/a and i was turning the car on everyday to keep the fuel pump from dieing while its siting in my driveway. one day i went to turn it on and it started up normally. i let it warm up but the idle never returned to normal it kept bouncing between 2000rpm and 2500rpm for some reason. so i poped open the hood to find that the alt belt was ready to snap in two so i figured that it was probably loose so i changed all of the belts two days ago but it hasnt done anything. also my battery is dead so i had to jump it to get it started. aparently the guy who had it before me stole some guys battery out of a honda civic. so it isnt the belts it could be the battery but the volt meter on the gauge cluster is reading fine maybe i need a new alternater or i have a vacum leak some where please halp me

 

Take a multimeter and measure voltage at the alternator post, with the engine running. It should be around 14 volts. A fully charged battery on its own will have about 12.5 volts. The cranking amps rating of a battery only matters on startup. Once the engine is running, all load is taken up by the alternator.