Put a new plug in one cylinder that is easy to get to when hot. Kill the engine at the stripe, coast off and pull that plug. Then you will know which direction to go.
normally if my car spins the tires I willbe slow to 60ft but have the same times from 60 to 330 and from330 to 660. This time I was.04 slow from 60 to 330. The reason I am wondering if its real fat is the humidity was climbing as the day went on. The more the humidty rose the slower I got.