89 240sx with rough idle problems upon cold start

[sr20dreams]

I have a 89 240 sx hatchback only mod right now is an Injen intake. The car has 160k.

My problem is when I start my car it idles high then low and just keeps on doing it until I pump the gas. But I pump the gas and get no response for a couple of seconds and then I'll rev it up and the car will idle fine. Any help would be a great help thanks.