nope :)
coolant temp sender would be the most likely cause...

if coolant temp sensor was fcuked wouldnt the ecu warning light come on?

Dirty injectors would make it run lean. As would an air leak.

Coolent temperature sensor could make it run rich as it would act as if the choke was on.

ECU light on?

Using loads of fuel? Is is at idle?

or maybe even a problem with the injectors...try some injector cleaner

and doesnt the air flow meter play some part in the mixture aswell??

another thing check for any splits in air pipes, i had one in the piece between the air flow meter and the inlet manifold which would of altered the air intake and gave my car a small misfire. if u rev the engine with the bonnet up u should be able to hear if its suckin any air in that it shouldnt be

but like trl said how u know is running rich?

First thing I'd check is the air filter....is it dirty?
How do you know it's running rich?
If it was during an MOT, did it fail? Was it miles out?
We need a bit more info.
It could be a duff CAT.

Tony

i know the mixture is set by the ecu but my x16xe is running rich. apart from cam timing what else can cause this? which sensor controls/ reads the mixture and where is it?