Ive had this on two K engines now. The first one I discussed above was in a civic circuit car, refitting the factory balancer fixed that one. The second one was a Juno sports car so no almost no flywheel and no room for a damper on the front, on that one the owner had to mess around trying a few different ideas to isolate the throttle. The final solution was a bracket to support the manifold (it was underneath and connected to the block with a rubber mount at one end), and he also made some sort of soft plastic/urethane or similar spacer between the throttle and manifold. From memory it also had some soft "washers" under the nuts a bit like a cam cover has.
