98 is different than 99-02 the maf tables aren't the same. But you could swap the wiring harness to run the 98 pcm. Should put headers on while your in there.
This X2
2005 GPGT- Top Swapped Click me!15.5 @109
2002 GPGT- slow and stock
1993 Oldmobile 88- exploded the diff @158k GPF Resident Flowmaster Troll