This has trouble written all over it...
Try to get more details on the meter,
The X3Z and A9* computers do not use the same aftermarket MAF 'calibrations'.
If it was properly setup in the 93 Cobra, then it will not work in your 89 (assuming an A9* ecu).
Find out what brand the meter is, AND what injector AND ecu it was cal'd for...
jason