idling at 2000rpm

[anthony]

My car has recently started idling at 2000rpm until warm. I.e about 3-4 minutes then it will return to normal 1000-1300rpm.

I recently took the air filter pipes off to get to the coolant level sensor to resolder thr wire back on.
 and i can only think that i might have knocked something?

Does anyone know what might be causing this?