87 f-150 Will not start.?

Battery, cables, solenoid and starter are new. The truck turned over and ran up to 2000 rpm which was odd and I heard a slight clunking sound, pretty dull but enough to get my attention, then the motor shut off and will not turn over. I can hear the starter engaging but can't tell if it is spinning or not. Wondering if my flywheel gave away or what?