340 tunnel ram issue

msd blaster 2 coil, hei msd dist, msd street fire wires 8mm, and it ran fine no issues untill one day. ex: drove it all day no issues, parked next day went to start car and noticed this. all i have done so far is check plugs, check wires, and play with timing and i did timing by ear not with a gun. prev owner told me he just replaced plugs and they are autolite's and he said he used short plugs not long ones that were in it before. i have not tried to change plugs since they are new and if it were plugs why would it drive good one day and not next? wouldnt it do it from when he changed them to new plugs?