Ford Fiesta 1.25 1998 Pick Up Problems

[Uk174]

Hi folks, forgive my ignorance but I am new to these forums.I have just bought my daughter a 1998 r reg ford fiesta 1.25.However I have now noticed that for some reason or another when I drive the car and want to push the revs in any gear the car seems to pick up speed but then seems to stop at a certain point after which it seems like the car is being held back almost like an inhibitor is in place.In first and second gear it is more noticeable but is still there in the other gears too. When driving I cant seem to push the revs over 3500/4000rpm ,however when in neutral i have no problems with the revs and can easily rev it upto its limits.The best way i can describe it is as if the is some sort of rev inhibitor in place which is stopping the car from picking up speed.Would appreciate feedback as to what may be wrong and how much to fix.Thank you.

[Uk174]

Sorry i forgot to add that there are no warning lights showing on the dash ,the engine management light is not on.