I realize it's a stretch, but the manufacturer of the locking lug nuts has changed the design of some of their locking lug nuts, so that the weight is close to that of a stock lug nut. I believe I read about this on a Mustang web-site. (not sure)
However, it is worth a shot. I took my original locking lug nuts off at the same time I lined the valve stem up with the yellow painted stud, and my vibration problem went away.
Also, I have a bunch of the stock lug nuts in almost new condition.
You are welcome to have them, if they fit your Mark.
Steve - TCCoA member
2003 Crown Vic LX Sport
1995 T-Bird LX 4.6 retired at 247,888 miles
Thanks for the ride !