Car stalled after new engine, clutch, battery, installed. Won't start

What is your question?

Car stalled after used engine, new clutch, new battery, new radiator, hoses, etc... put in. $3022.00 worth. The car tries to start, but won't. Had to tow. Now it starts, but repair shop says it will stall again. Does not show a diagnostic code. Now they say it could be the ignition module, or the crank sensor?? Does not know, for sure, says to replace both, and wants another $700.00. What if that doesn't fix it? I'm too far in financially already!