I have a newer bseries motor in my 92 civic hatchback. When i come to a stop and car is idleing. The rpms seems to start surging up and down from 1000 to 2000 rpms for a couple of times then come to a regular idle in about 800 rpm range or keep surging till i start driving again. Car runs fine only at a idle it seems to act up. I played with the idle pin but no luck what could it be??

any help would be appreciated

Keith