My Z ran, but the engine would shut off after letting go of the gas and if I left the car in idle, it would shut off after about 15 minutes. I was about to look at the vacuum lines when I ran out of gas. I added gas and it would not start. I checked to see if there was spark to the plugs, but there wasn't. So, I began to think the rough idle and stalls could be attributed to a degraded PTU, and I was looking for confirmation.