CA 20 Idling tooo fast Maybe Vacuum advance

[Robi1]

Gidday Chaps. had a guy bring in an 89 Bluebird Ca20 running like a drag car 2000rpm. problem wasn't carbie. retarded distributor brought it down to1500 rpm when i removed vacuum pipe brought it down to 1100 rpm. still runs <>ok. Is there a tension spring somewhere in the advance mechanism. or could there be a problem in the electronic control module. this guy used his car to jump start a few other cars. I think 89 used CDI type igniter unit. car is ok without the advance BUT not brilliant. this is just the standard single spark model but the head is same as for twinspark with one side blanked off. any ideas guys much appreciated