consistant misfire out of nowhere

I'm having trouble with my slant six in my 72 duster. while I was out driving on saturday, it was running fine and normally. I stopped at a stop sign and when i accelerated again it started bogging, misfiring, and the car stopped moving. Also the RPMs would not change even if I floored the gas. it finally died and after many attempts to restart it to no avail, I consented to have it towed back to my house (less than 1 mile back). once it cooled off in the garage, my first inclination was to check to make sure it was getting enough and clean fuel, I checked the fuel pump, and replaced the filter and with that I could start it as long as I held the gas pedal to the floor. I checked the distributer rotor, that seems good. My next consensus was bad spark, seeing that the plugs only had 100-150 miles on them I replaced the ignition coil (which was the original one) with one from Accell (the yellow one) and now it starts without holding the gas, runs and I can rev it a little but still the bad misfire. Has anyone had this issue before? and ideas?

thanks,
Jonathan