1999 Jeep Cherokee hard to start

Hello, my jeep cranks over slow, wont start unless you hold down on the gas, when it does start, there is a big puff of black smoke, and it runs rough for about 10 seconds, if you let off the gas it dies. If you rev it up after it starts, it acts as if its "clearing its throat" and runs, idles fine. I've changed the air filter, cleaned the throttle body, put in a bottle of fuel/carb cleaner, and changed the dist. Cap and rotor. When I pulled the dist, cap, the rotor looked burnt, and actually had a hole melted through the top! There was melted, shredded plastic in the inside of the cap, could this be a bad coil?