just bought a 1993 tbird, has new battery, has new alternator. was driving home and blinkers quit. then the air conditioning quit. then the voltage gauge started to dip near the 8. turned it off. wouldnt restart. jumped it, ran fine- with blinkers- then 20 minutes on my way, the air and blinkers quit again. just checked all the fuses and they look fine. what now? also, lighter and rear defrost dont work.. but all the fuses are fine...

 

Sounds like a bad fusible link, a dual filament bulb with a blown and crossed filament or some wires that fried together. Start with the easiest and check the fusible links, then any brake and turn combination bulbs, then last try disconnecting the battery and tracing the wires from problem sources like lighter and rear defrost,etc.