VIN number says 6cyl. but shows as a 318

It could be a factory screw up or somebody has done a V8 swap and put a V8 emissions sticker on it.
Post a picture of the VIN tag and also the door sticker. Cover up the last 6 numbers before you take the picture. (Keeps the rif-raff away)
Also one of the emissions sticker.
Try to find the broadcast sheet. Usually under the back seat or on top of the glove box.

We'll get to the bottom of this.