I have an '85 with about 80k miles on it. When I start it up, there is a hesitation when I step on the gas (when it's cold or hot). When it's up to temp, it isn't as bad, but it definitely smells like it's running rich. I replaced the oxygen sensor, and there are no trouble codes showing. The idle also constantly cycles from 5800 to 7000 and back.
Does anyone have any advice on what to look at first?

 

i would check the EGR valve and the fuel injectors