If that doesn't work, you should try and, clean the throtle body.
You shouldn't need to take it out though. In the shop we have a throttle body cleaning device, but before we got that we would use some good carb cleaner and a tooth brush to clean the butterfly plate, and all of the little holes. then wipe it clean with a shop/rag.
Just an idea, with out looking at the problem we can only guess with you.
Good luck
