Tachometer/RPM jumping

93 SI had the car about 2 weeks, my tachometer is jumping like crazy under acceleration, for example it shouldn't hop for 2 to 5 or 4 to 8k etc. Obviously it runs off the distributor, which cap and rotor look new but the car sat for 6 years. Any advice? Ignition control module? Quite annoying when I'd like to shift at a higher rpm and can only go by sound.