Agree with JSMith. Oil evaporated inside the MAF and on the wire that measures the air. Remove KKM and install stock box and reset computer. If this changes nothing, take your MAF off and clean carefully! Reset computer and try again!

Step 2 Fuel injector cleaner/ 2 tanks!
Then fuel filter replace.
I skipped the sparkplug change as you already had this done.

These are all inexpensive fixes and you have nothing to loose.

**** Just remember, you are under waranty and can stick this problem to Ford until pigs drive contours (if you have to) wink

2001 Cavalier
150-175 more kms
per tank of same size
Pioneer 12 CD Changer

SOLD Green 98 Mystique
GS Sport
Zetec ,ATX
885 Fogs mod.
Hi beam mod.
205 15s