Here is another possibility...
Depending on what kind of rims you have they may need hubcentric rings for the MN12 application.. Check with the manufacturer and then check to see if they are there ... if you are supposed to have them and don't have them, get them and put them in.
Hubcentricity: A wheel that is mounted on a vehicle, should be hubcentric, to assure proper fit, and hence will eliminate such issues as vibration, shimmy, and erratic tracking! A hubcentric fitment, is one where the interior of the backside of the wheel - referred to as "centerbore"-is an exact fit to the "hub"-that protrudes from the mounting surface of the wheel. The relevant issue here is that the WEIGHT BEARING of the wheel on the car is done on the HUB when it is "mated" to the wheel! This has to be an exact fit.
Just a thought...
'96 T-Bird LX 4.6L Alive & well & living in S. Florida
N/A: Renegade NPI heads/Comp Cams; OEM intake manifold; Bolt-ons
245 rwhp; 13.713 @ 99.35 (Commerce, GA - November 2003)
BLOWN: Renegade NPI heads; Renegade shortblock; Intercooled T-Trim; some other stuff
Pump Gas Numbers - 547 rwhp / 525 ft.lbs; Best Time - 11.388 @ 118.68 (Commerce, GA - November 2007)