1991 Cadillac Brougham Engine Performance

My car is fouling spark plugs within a 4 month period of replacing them and I have upgraded the heat of the plugs to burn hotter. The plugs are black and soot covered and they can be cleaned and reused but my issue lies in it fouling them. I ran a compression test to see if the piston rings were bad and all of my cylinders were at 195 and 200 which is close to the 9 to 1 ratio they need to be. My valve seals are not bad and I do not get blue smoke at all so they are fine. I changed the pcv valve to see if it was causing pressure in the crankcase and I am unsure of the result. I was thinking it may be running rich cause the spark plugs get carbon fouled and not oil fouled. I have changed many sensors but the only two I have left are the MAP sensor and the fuel pressure regulator. Any help is appreciated. I thought they were oil fouled plugs but they are getting carbon fouled.