Car won't stay on after AC compressor replacement

What is your question?

Recently, my AC compressor went out. I decided to try and replace it myself, and I replaced the compressor, accumulator, and orifice tube, and after putting everything back together the car ran! After driving around for about an hour, the car shut down and would no longer remain on. When I start the car, it starts and runs normally, but rather than idling, the RPMs immediately drop to zero. If I rev the engine, the car stays on and even drives, but as soon as I let off the gas the engine shuts off. Any ideas about what to do?? Thanks in advance!