So lately whenever I let off the accelerator by either holding down the clutch or coasting in neutral the RPMs are dropping super low, frequently as low as 500. It normally never drops below 800 or so while driving or at idle. A lot of times it fluctuates from 600-800 while coasting in neutral. Any ideas what it could be? I tried listening for any vacuum leaks under the hood with the engine running but it's so loud under there I really couldn't decipher anything.. Thanks!