I recently had the same problem with the car stalling out when letting off the gas, right after I had replaced the PCM. After spending hours trying to figure it out, it boiled down to a crack that had developed on the back side of the air intake after the air sensor but before the throttle body. Make sure you have everything buttoned up and sealed there, it appears that this sensor is very sensitive. I hope your problem was easy to fix as mine??? Good luck!