Rover revving problem

[dal]

Hi, I have a Rover 400 si & I have a problem with the throttle, it's fine with ordinary driving but once I get stuck in traffic after about 5 minutes the engine idles at about 2500 revs ( I can get it down to normal revs by blipping the throttle but when I start driving again then stop it's back up to 2500 revs ) it's not the throttle cable I've removed it from the throttle mechanism and it operates nice and freely.

Has anyone had a Rover with this problem, if so what was it & how much did it cost to sort out.

Regards.

P.S BL**dy cars

 

[dal]

I had this on a 620 ti. I had to replace the coolant temperature sensor, and then it stopped.

Cost £6 for the part from Unipart (PWRPETS134)

Someone else has mentioned the coolant temp sensor, was it easy to fit ?