How many miles does it have on it? My 90 I just bought is doing something similar to this. I plan on it giving it a full tune-up (plugs, wires, cap, rotor, fuel filter, air filter, pcv valve, adjust valves, etc..) this weekend since it is a holiday weekend. I have all the parts in my room waiting to be put on. I hope this helps.
You can try throughing some fuel injector cleaner in your tank for a few fillups. I usually make that standard practice when I buy a new old honda.
2-3 tanks of fuel injector cleaner and use Seafoam to clean out the break booster portion. Don't put anything into the oil. I'm always wary of that.