when i start my 03 civic ex 1.7 vtech idles rough an almost stalls on 2003 Honda Civic

when i start the car it starts idle normal at about 1000rpms an then starts to idle rough an goes to like 500rpms an almost stalls for like 30 secs then comes back to normal an somtimes when u start driving at like a stop light or etc.. it starts off putting like its going to stall then goes fine what could be the problem?

Asked by for the 2003 Honda Civic
Check engine light? Plugs? EGR valve faulty? What maint. has been done? How many miles on it? A/C on or off when it idles low , or no difference?
no lightts on a/c not on when this happens and the cars got 132400 miles all fluids are toped off last maint. was oil change at 13100 miles. I bought the car used with 128xxmile