Hi had to change the battery on 52 plate focus ghia as the old one kept dying, bought the appropriate battery and fitted, now on starting the rpm goes up to 1800 and after 20 secs or so goes back down to 800 ish, but when i am driving the rpm is fluctuating high sometimes and when i clutch to change down the rpm continues to stay high and the same at traffic lights its hitting 1800 and then taking 20/30 secs to drop to 800? there seems to be nothing wrong with air intake!! any ideas? thank you.
Yes would check for an air leak then I would need to see the vehicle