I have a clutch question...most of the time it works just fine...when I'm driving it shifts with no problem. It's when I put it into neutral at a light or something...or if it's sittling idling...it doesn't want to shift. Most of the time if I rev it a bit, it will shift. Sometimes I need to put it into reverse to stop the engine, and then it will shift. I replaced the bushing under the shifter, and so when it does shift, it shifts like butter. I replaced the clutch master cylinder a year or so ago...could it be a vaccuum issue? How do I check it? Any ideas would be appreciated.