88 Civic slow idle, and sputtering

Hey guys I am having some weird problems with my 88 civic, it's idling slow and seems to be running rich, it sputters bad in the lower gears when accelerating, but on the highway it runs great. I just had the 02 sensor replaced, and it did not seem to help much. Any ideas what could be causing these problems? Thanks in advance!

I just noticed some oil at the bottom of my number 4 sparkplug. Could this be causing the problem?

Anyone?

Help!!!!