I just installed a clutch in my 944 and it starts and immediately dies

There is a flywheel sensor on the bellhousing that you either broke, disconnected or have the gap off more then likely.

Be sure that you reconnected all the ground wires correctly.

I had the exact same problem with mine. I had to go out and buy a washer and glue it to the sensor to set the gap, then set the sensor bracket, take the sensor back out, remove the washer, and reinstall the sensor. It worked beautiful. If you don't do it right it can snap the sensor off and it's around $79 to replace it. so take your time and do it right the first time. I went through 5 of them before I learned my lesson.

starts and dies?what do you mean?

u didnt put the starter back in right when u got to the slave bleeder recheck youre wires

Hope you didn't install the friction disc backwards. It reads on the disk "This side toward engine or flywheel" I hope you remember reading this.