I have an '81 Silverado 6 cyl auto trans. I only (?) get 11-13 MPG. Is this normal? It has an electronic vac advance (at least that's what I think it is). It's part of the dist. cap, but it does not look like an "old fashioned" vac advance The vac hose is disconnected, and plugged. The truck runs great! But the milage is killing me. Any help would be appreciated.
