ok this is pretty much driving me nutts . 77 shovel . starts rite up idles fairly good . while going about 30 she will buckle and buckle . though maybe carb rebuild carb (s&S) reset the points and gap even tried swapping carb to another one does the same thing . havent delt with points in a long time , someone said something about a plate behindn the points that locks up and it will cause it havent taken apart yet . also points are timed far advanced as they can go runs better there . shes fine if you give it gas and want to go 100 mph . whats causing this .