"Yes they would run away at idle power, I think the main problem was actually keeping the taxi speed down without duffing the brakes."
For your interest, it was SOP to shut down the no.1 engine after landing and taxi in with the no.2 at fast idle (58% on the throttle detent) in order to keep the AC on line via the air-driven turbine.
If it was necessary, idle thrust could be selected with the loss of AC.
Under such conditions the aeroplane did not run away from you. If the 'chute had candled on landing then one had to be aware that the brakes were hot and caution was required. The Lightning did not have nosewheel steering and taxying was achieved with differential braking.