If by misses you mean rough idle...I had a rough idle after warm up on my 87 420 that started a few months ago. Waiting at a stop light it felt like the engine was going to die. Did a search here and all roads pointed to a dirty idle control valve. Found one post with pictures if you dont know what it looks like. Takes 5 minutes to pull out. Soaked it in carb cleaner and cleaned the inside with Q-Tips. Popped it back in and no more rough idle!