problem with fiesta zetec 1.25 1997 r

Blocked exhaust / catalytic convertor has collapsed. Check and replace the air filter first of all (cheaper than an exhaust).

Had the same thing recently with my (daughter's) Fiesta.

The fault was the ECU being in 'limp home' mode because the Coolant Temperature Sensor had died, a common fault apparently.

Quite easy to change, a bit awkward to get to since it's under the coil pack.

Disconnect the battery when you start the job (sort out your radio code beforehand!). This will let the ECU forget the error codes. Then once you're done, let it idle till the fan has cut in twice. After that go for three or four miles of mixed driving. All this lets the ECU re-learn its parameters.

HTH Cheers John

Ah well. Looks like you have an air leak upstream of the air flow meter, or the meter itself is shot. Usually the engine doesnt limit the revs, it just stalls when the throttle is applied quickly, but the revs can be 'nursed' up.

Probably just a different design, manufactered by a different supplier, make sure all is definitely well prior to forgetting about it.