Check when your changed the points if there was a separate spring that clips on when I did mine I thought because there was a copper spring already attached and a metal spring in the box that it was for several applications. So I installed the points and had the truck running fine at idle and when I accelerated the truck would backfire and cough. Only when I put the spring steel on did it run proper as the copper piece was not putting enough pressure on the lobe of the distributer shafts to open and close properly
