Hi there, I appear to have a multitude of different problems of which I am sure are related, but not too sure where to start.

The problem appears to be the idling which very slightly goes up and down (not so much hunting) whilst on tick over, there is also a very slight buzzing sound from the fuel pump when the revs drop, whilst driving the car the headlights go bright and dim, along with the heater blower being a strong airflow then dropping (repeated) this all coincides with the noise, the lights and dip in the revs.

The higher the revs go, the faster the cycle of problems, not sure if connected, but the speedo occasionally drops then picks up seconds later along with the battery light that has occasionally come on. There's also the occasional misfire.

The fiesta has done this for the last week, but was otherwise fine before hand.

Any advise would be greatly appreciated. Tia