Try to clean the MAF and the ISV see if this solves the problem, dont touch the MAF though just spray electrical contact cleaner on it, you can buy it from halfords etc, make sure it dries before you start the car because ive heard it can cause a fire etc if its still wet. Doesnt take long to dry though. Clean the isv with carb cleaner, making sure you have cleaned all of it fully, this can be touched, hope this helps and good luck with solving the problem