Kenseth finished third in the race, which included eight cautions for 39 laps. After practice and qualifying speeds soared over 200 mph on the newly paved surface at MIS, teams switched left-side tires for the actual race.
Earnhardt seemed agitated after a special practice session Saturday night following the tire switch.
''I was desperate in that last practice to get something to work,'' he said. ''When it ended, I still wasn't really sure if we were where we needed to be. I woke up this morning, just antsy, not knowing how this was going to play out.''
It worked out just fine for Earnhardt, although there were problems around the track almost from the start. The race started a couple hours late because of rain. Kurt Busch -- back from a one-week suspension for verbally abusing a media member -- went into an early spin. He finished 30th.
Joey Logano, who won last week's Sprint Cup race and Saturday's Nationwide race, was out of this one after a multicar crash that brought out a caution from laps 127-132. Almost immediately after the restart, Denny Hamlin's Toyota went sliding across the grass and caught fire. The flames were extinguished and Hamlin got out of the vehicle OK.
Ambrose finished ninth after a qualifying lap of over 203 mph. He was the first Cup driver to win the pole at over 200 since 1987.
Earnhardt led for 95 laps. Nobody else led more than 38.
''This is incredible,'' Earnhardt said. ''I just didn't know when it would happen. I knew it was going to happen, just didn't know when.''