A lot of people are pointing to the firing order/wire routing and I would agree. I would also check the wires and make sure they aren't arcing out.
The 1986 cougar had a 1-3-7-2-6-5-4-8 firing order (351w/302 HO firing order)
Most carbed 302's are 1-5-4-2-6-3-7-8 as a standard 302.
Please update us if its corrected or still a problem
Also check for vacuum leaks, fuel supply, reset your distributor to factory position and start fresh.