The customer is complaining that the car stalls when he stops at red lights.
When I checked the plugs (NGK R) and they were white.

The car idles without any problem and I couldn't get it to stall on me...
No vacuum leaks, fluids are ok. No check engine lights codes.

Weak fuel pump??

I am planning on doing a complete tune up (short of an O2 sensor). What would cause the car to run lean like that???