Back when Pratt was developing the PW4000/94" (767/747-400), they used the very first 767 (VA001) as a flying test bed - PW4000 on one side, JT9D-7R4 on the other.
Very nearly ended in tears during an early test flight - at about 50 ft. during TO, the PW4000 surged big time - the PF calmly reached over and pulled
both thrust levers to idle
The other pilot quickly slammed the levers back up - the JT9D slowly pulling the aircraft skyward while the PW4000 kept surging away.
The PF is question was later removed from "Experimental Flight Test"...