Q45 front end shake

[Mark86T]

My 96 Q has a front end shake between 55 & 65 mph. It's smooth before & after those speeds. New wheels, tires, Tokico struts, Eibach springs, alignment. Had the wheels back 3 times for rebalancing. Put on my Z front wheels(new wheels & tires there too) but it still shakes. MUST be suspension. Can't find anything loose or obviously worn. With how expensive all the parts are I don't want to try the hit or miss replacement game. Any thoughts? Thanks.BTW, the wheels are 18x8s with 245/40s - so are my Z front wheels which I also tried on the Q.