Fiesta engine revving wildly

[johnross]

Fiesta 1999year Encore 1.3
Engine Endura

Water kept dropping in expansion tank so got car into a garage, just been fitted with new cylinderhead gasket and replacement head (old was cracked). When mechanic restarted engine it starts ok and runs for few seconds then.... engine goes crazy! It starts to rev high very quickly, Have to turn off Ignition immediately. Is it something to do with TPS? have changed it with another 2nd hand one but same thing happened. Could both be wrong, or have been fitted wrongly? Do the engine management units ever go on these cars? They've said they have cleaned TPS connector plug. Can this happen if the TPS is not installed correctly? (It goes on with a little twist in the right direction)
All advice greatfully received
John

[Zad]

Idle control valve being set to fully open because the ECU thinks it is dying? I suppose if the throttle position sensor were back-to-front it would think it was fully open and give it everything, but it would still need air to make the engine run so fast. Maybe a pipe got left off when they were refitting the inlet manifold? Have they had a look at the throttle butterfly, to make sure it isn't jamming open?

[Jon GT2]

I would suspect an air leak as Zad has said,iscv gasket left off?Inlet manifold gasket not seated correctly?