1996 Other Saturn Models car won't stay running

Computer problem
1996 Other Saturn Models Front Wheel Drive Automatic 114k miles

My '96 Saturn SL2 with 114k miles will start right up when I turn the key, but then as soon as I release/let go of the key, it will shut off. I can keep it running by stepping on the gas pedal, but it shuts off immediately when I release the pedal. After letting it run for many minutes with foot on gas, thinking it might be the temperature sensor, it began to idle itself and ran fine for the next day. It did this sequence of shutting off about twice a few weeks ago, but no major probs until yesterday. Error codes via handheld computer are P1312 (manufacturer-specific power train trouble code, I was told) and P0007 (fuel shut off valve A, control circuit high). What does this all mean? What needs to be replaced/fixed? It had no problems with starting and the temp gauge looked fine this morning (registered cold to start). Thanks for your help!