Ford Puma 1.4 Head Scratcher

Hi, I'm currently building a 1.4 puma rally car I'll be using the standard 1.4 engine but I'm struggling to get it running right. It idles at 1500rpm and when dropping from higher revs holds at 2000rpm only noticeable thing is when the clutch is pressed the revs drop straight to 1000rpm but then climb back to 2000rpm currently I have changed the tps and icv every vacuum pipe coming off the throttle body and cleaned the butterfly I've also cleaned the maf I've replaced the clutch position sensor and the power steering sensor is fine but the problem is still the there I've tried to disconnect the maf and speed sensor but both just make the car stall straight away, any help would be really appreciated also today I've changed the camshaft breather under the inlet manifold that did have a split