I have a 1978 mercruiser alpha 1 305 chev v-8, last week it started to run really rough, I changed points, condenser, rotor arm, cap, plugs, fuel filter, engine still runs same OK at low speed but as I hit 2000 rpm it starts to "gasp" for air and run very rough. Checked dwell, its at 30, In line with what a mechanic told me. Any ideas
