Engine shuts off

Maintenance/Repairs
1

I have a 2003 Ford Focus with the Zetec 2L, 16 valve. When the car is warm and I put it in neutral or park and take my foot off of the brake it will occasionally shut off. Not stall, but shut off - as though I turned the key. This doesn’t happen every time; it usually doesn’t. I have no other drivability problems and there are no warning lights or engine codes. The ideas I have are:

  1. vacuum/ brake booster leak
  2. MAF problem or dirty throttle body
  3. something weird going on with the transmission shift interlock mechanism.

Just curious to see if anyone has suggestions. Thanks.

2

Sounds more like it is related to the ignition lock or maybe a battery connection

3

A vacuum/booster leak would set a P0171 lean code
A bad MAF might very well set a code and cause driveability complaints
A dirty throttle body would cause a rough/high idle

You may want to hook up a scanner and check for stored codes