Sure sounds like the throttle linkage came adrift.  30 years ago a friend of mine was flying a 150 with his girlfriend and owner of the plane.  Throttle linkage fell off in cruise not far from the airport.  He set up for a landing on a vacant street in a subdivision under construction and had the landing made.  The copilot kept fussing with the throttle and it caught, so he aborted the landing, climbed back up, leveled off and then pulled the throttle back.  It fell off again and this time they ended up in a field upside down.  Ever since then I've been paranoid about throttle and mixture linkages, putting safety wires all over the place just in case one of the other safety wires comes off.

Gary Casey