My 82 PA 454 4 bbl just had the same problem it was just a spudering and coughing,and lots of black smoke out the tail pipes enough to cover the grass in the yard. If I held open the butterfly it would work it self out of it. Turns out it was the choke pull off. Replaced it @ $35.00 bucks and now she is starting and running just like the summer time. I would try starting it with the air cleaner cover off and watch and see if the butterfly starts to open at all or try and open it with your fingers and see if she starts running better. By the way she (ours) has 2 fuel filters under the passenger side of the MH and then there is one @ the carb. JMO hope this helps, maybe, let us know.
Good Luck, Tim
Opp's is this a fuel injected motor? is so sorry
