ford ka 1998

[kain]

i have a ford ka 3 on a s plate.it has suddenly decided to under revve and jump when driving,it also cuts out when standing.i have had a idle air unit fitted,also a electrical car enginer wire the car up and he has reset the engine.the throttle control sensor has been cleaned,and its coming back as fine on the mans computor.and yet when driven its just as bad has anyone got any ideas as to the cause of the problem .its now ticking over fine but still is still bad on jumping ect.any thoughts gratefully recieved.