I have a 1992 Z28, with 5.7 TPI. When car starts voltage is great at about 14.5 volts, however when the car warms up, it steadily decreases, going all the way to 9-9.5 volts. It gets so low that car starts missfiring and sometimes dies. When I give it a little gas, it picks up a little, may be to 11 volts but no more. I read some of the posts mention bad ground connectors. Mine looks good. Is this simply a bad alternator issue? Thanks!

 

Grounds are a good place to start. (Unfortunately looking at a ground will not tell whether or not there is connection between the mating surfaces). While the engine is off, with a good quality volt meter, check the voltage at the battery, take note of the voltage. Move the ground lead on the meter to clean metal on the engine block and/or chassis. These voltages should read the same within a ½ a volt. If not most likely there is ground problem, cause by ex: corrosion, loose connector, bad cable, ect.
If you find you have a good ground, then have the alternator checked it may have a blown regulator.

Good luck!