Fiesta 1.25 Zetec reving problem

[Gad]

Hi Guys

Just a quickie anybody had any experience with the 1.25 zetec fiesta not revving at first then suddenly surging. Its not my car its my sisters just gone through the usual plugs leads fuel filter oil change etc but problem still seems to be there more so when the car is cold. Should i be looking for something else maybe some sensor on the air intake or throttle body ???
Cheers.

[nighthawk]

Have it checked out on a code reader.

depending on the build level of the car, it could be a number of possibles.

MAF sensor or MAP sensor could be slow to react to changes in air flow or pressure, that'll give sluggish engine performance.

BUT, there are lots of other possibles.