Hello all, it's been a while

My car has not been driven much this season, and one of the reasons is that it has this strange behavior where the engine almost stops. It usually doesn't happend on shorter trips, but on longer (say over 30 minutes) it will start doing that, and when it first starts - it will happen repeatedly. When I say it almost stops, I mean that it is surging to below 500 rpm before picking up again. It usually happens at fairly low or no throttle.
I also remember this happening last season occationally on long drives.

So, what can be causing this - can it be the fuel pump ? It has never been replaced in the 11 years I've had the car. It has new plugs, cap and rotor. CES light is not coming on when the trouble starts.

Any thoughts/ideas ?

Thanks!


Ken