Doubt it's MAF, I think you will actually find these have a TMAP anyway. It should have the Zetec-S (Sigma) engine in it. I would check the vaccum pipes, these are common for splitting and causing air leaks, causing the problems you describe by the PCV.

ISCV is at the front, you will see it's got two bolts and an electrical connector.

If not I would look toward the VSS, although you normally notice problems elsewhere when this is the culprit.

Martin