rpm issue? electronic?

Checked the resistance on the distributor and it is good also checked it on the coil and it was off by 0.1 so just in case I swapped it with one right in the middle of spec but still no difference at high idle I am reading about 650 rpm and at low about 200 rpm which is way off. any ideas? If I wasn't worried about the drivability issues this might imply I wouldn't worry about it but low amperage or voltage depending on what a tach reads most likely means there is a problem somewhere.