1995 Toyota Celica Cuts off when the Engine warms up?

[Garnett S]

I drive a little 1995 Toyota Celica GT, one day I was sitting with my car in park after driving it a little while and it was as if someone just reached up and cut the switch off, It just died. We got a ride home, my dad took me back about an hour later to get it and it started right up, drove it home, pulled it out to his shop and once the engine got good and warm it did the same thing, He gave her time, let the motor cool down and she fired right back up. Can any one tell me what could be causing this and what I need to fix this? I'd really like to find out so maybe my dad can fix the problem instead of having to take it to a shop.