After a couple cranks in the morning my car starts right up. Goes into high idle like it should and runs great with no missing etc. Then I turn it off and it sits for a short period of time ie: 1 hour or so and try to start it again it is difficult to start. It cranks numerous times and then I put the pedal all the way to the floor and it will eventually start. Black, sometimes blue smoke comes out the exhaust pipe. It shutters, spits and stinks and will eventually clear after about 30 seconds and will run great. And will continue to start this way until the morning when it starts up great and runs fine. When the car is running, it runs great and doesn't burn an ounce of oil. The mechanic replaced a couple of plugs, installed a new coil and put 2 cans of Sea Foam in the fuel tank and said to run it hard for a couple of days. Well, it did didley So, what do you think it is and what might the repair cost?