engine problem

[woodchopper]

I have a kit car - when it is the engine is cold it runs ok. But as it gets warm it seems as though the throttle cable or mechanism is sticking - I have checked it - it isn't so that would mean it would have to be something else - just not sure what though, any ideas?
It is a K series 2L rover engine with only 900 miles on the clock.
It is a bit of a nuisance when you are trying to sow down and it doesn't want to.
Thing is if the engine is switched off and restarted it is fine.

[ianess]

Could it be a faulty lambda sensor making the engine react as if a choke cable was pulled out [enriching the mixture] causing it to rev much higher than normal?
I had this problems years ago with a Nissan Primera and it wasn't a lot of fun when it was fighting you against the brakes. Luckily it was easy and cheap to replace the sensor.....apparently they're not repairable and must be replaced.