Tony Richardson

When my Banshee gets warm it starts running bad in the mid range. Everything runs perfect untill about 170 degees water temp (Ihave a temp gauge). It seems like it starts missing and not wanting to accelerate. If I downshift and get back on the pipe it runs fine and it idles warm, just no mid range. Throttle pos. does not seem to matter. If I let it cool down it runs great. What can be causing this?