Lately I have been having an issue where, at startup, the voltimeter only shows like 9 volts.  If you tap the throttle for a second, you can get it right back to 12-14 volts.  I replaced the battery just a few weeks ago (I was having the problem before that also).  This weekend it stuttered a bit at startup in a parking lot, and I noticed that my clock reset to "1200".  Sound like time for a new alternator?

It sounds like alternator brushes worn to the point of hanging up a little.  Especially if you have the original alternator, you might just want to rebuild your current (no pun intended) one.  Most quality auto parts stores carry a kit with brushes, bearings, and sometimes even new electronics.  The only challenge in doing it yourself is getting the big nut off the front that holds the pulley on.  An impact works if you have access to one, otherwise wrap the fan of the alternator with a big rag, pull it tight, and clamp it in a vise.  That will hold it without damage while you break the nut loose.

Good luck
Larry

Did you by any chance replace the alternator with a later model recently. Some of the newer, higher amperage alternators don't kick in until they hit a certain RPM.....

Sounds like you need to start checking battery connections, and grounds.
You can get your alternator rebuilt, but be careful where you go...alternators have a pretty high failure rate at most places...cheap replacement parts.
I rebuilt the one on the '74 myself, for several reasons. One, because I could, and couldn't see paying some else to do it.
Two, because someone else would screw it up( I wanted to keep the original finish, and numbers), and three...it only cost me like $12 for the parts! That was brushes, regulator and bearings!
On the '85, when it needed an alt, I just bought a reman. It wasn't original to start with, so I wasn't loosing anything.

Check your ground cable from the frame to the engine, on the pass side...Adams' Apple2008-04-01 19:29:44

I already gave all the underhood wiring a quick check and didn't see anything obvious. 

MAKE SURE BELT IS TIGHT ENOUGH WITHOUT OVER TIGHTENING.

I agree with Adam's apple - check the ground cable from your battery to the frame under the battery box. I replaced my battery and apparently just the movement of the cable during the battery replacement was enough to break the connection. It only takes a few minutes to remove it and clean the cable connector and the frame (with sandpaper) then put it back together. A lot simpler than fooling with the alternator!

Thanks for all the tips, I'll have a couple things to check on this week! 

I think I got this link off here?? I don't remember. Step by step alt rebuild.

Well I had some time on my hands this afternoon so I went out to the garage and checked everything over... PSU 982008-04-03 12:20:17