Honda City 04 A/T namamatay engine

Mga Sirs,
Patulong naman. Ride is 2004 Honda City idsi A/T. Minsan sa slow moving traffic nag-stall ang engine. Pag instart, ok naman ulit. Naka bukas aircon. New changed-oil, at palit ng valve cover gasket. Na modify na ang air intake eversince nakuha namin. Ano kaya possible issue?

Salamat in advance.

Regards,