Ive got a 91 camaro that when i go to start it sometimes it will start right up sometimes i turn the key and it takes 5 sec, maybe 10secs, just depends and i have no idea why. Sometimes it wont even start i need to turn the key off and try it again and then it usually works. When running the alt shows about 13-14 on the gauge or so when running, When i shut it off and then turn the key on it shows it alot lower like 8 or 9. If i start the car and shut it off a few times it will act like the battery is going dead, maybe it is. The battery terminals are clean and i just don't know where to go from here. I put all the info i know in here hopefully someone has an idea. Its got a 305 in it.

 

check your connection it sound like one of your ends is corroded or not tighten down all the way

 

Also check the connections at the starter. Might be a loose solenoid on the starter. Had this happen to me on an S-10.