Anytime you do any modifications on your car,
especially modifications like the mystery mod,
you need to reset the PCM.

Pull fuse #4 and #11 in the underhood fuse panel.
Leave out for minimum 5 minutes and then replace.
If you leave them out for more than 20 minutes,
the Auto Transaxle will have to relearn its shifting pattern.

Pete...

98.5 SE Sport Duratec ATX (P66L)
Black Clearcoat on Greystone
DOB 11/21/1997
DOP 12/25/1997
PIAA 510 Super White Driving Lights
SVT CAT-BACK EXHAUST (No Resonator)
DiabloSport Chip (LPQ4) - Engineered To Raise Hell
Too many other mods to list...
Sounds sweet, runs quick...
Crazy Horse Dyno @ 121.4 WHP/129.6 TQ