Revving Problem

[Chico999]

My car is very temperamental. Its usually fine but if i leave it running for say 5 mins, It starts to build up revs. Not just a small amout. Stays at about 12 - 1300 for a min, then up to 2000. And occasionally up to 4000 revs!!
Can anyone help me with this problem???
ta.

[Chico999]

Ahhhhhhh
Forgot to say, i have been told its the Engine Coolant temperature sensor. I dont really understand this because its only sometimes this happens. Its as if it thinks its going cold when it overheats......help!!!

[frankie]

i have the same problem.

either coilpack or lambda sensor.....think mines coilpack but to skint to replace.

[Chico999]

Ahhhhhh, wots a lambda sensor then?
sorta know what a coil pack is.