could be a carb problem. spray some carb cleaner in there and work the throttle linkage...you may want to change the fuel filter as well. it sounds like it's clogged up and maybe the fuel only is getting through when enough pressure builds up to push fuel through. this could cause the surging. also check all the vacuum lines for dry rot where they have cracked (or are just gone)
after all this is done if it still surges, you may need to check the timing.
i had a eighty something honda civic for awhile and i remember it doing this stuff...it was a sticking float needle valve or something like that in the carburetor. i replaced it but it was a real b!tch to get the air fuel mix right...it was confusing.
