Can't be 100% sure but I had a similar issue with a V6 Telstar I owned which turned out to be the actual
distributor itself. Assuming it's the same engine in the Cougar (pretty sure it is) the fault with the
distributor is to do with the internal circuitry, it has a silicone film over it to keep moisture out but over a period of time the silicone dries out forming fine cracks, moisture gets in and starts to cause issues. Has the car ever completely died on you and you've had to wait a few minutes before it will restart ?