Occasionally when Im driving around, say in 5th at 40 or so, the RPM's will be around say 2k. Ill put the clutch in and shift out of gear to coast up to a stopsign. The RPM will stay at 2k until I tap the gas quickly, then it will return to normal idle. It does this at various points in the RPM range. Would that be a dying TPS, dirty/sticky maybe?