The reason why engine races or poor response
1. The clutch is out of adjustment.
Car troubleshooting
As the clutch pedal is being released, the problem of poor response in conjunction with a racing engine is a standard sign of a slipping clutch. In other words, the clutch isn't grabbing well and therefore the power from the engine isn't transferred to the transmission well. A clutch can slip when it's either out of adjustment or worn excessively. Since the car was old but less done 50,000 miles on it, an excessively worn clutch isn't very likely (they don't wear out that fast). However, it's possible the clutch may be out of adjustment and thus, as said before, this can cause it to slip.What to do?
If this vehicle is no longer covered under warranty you'll need to find a quality shop specializing in manual transmissions. Have the mechanic adjust the clutch "free play". The free play is the amount the clutch pedal moves before the clutch begins to disengage (one to two inches is normal). This adjustment may very well solve the problem and best of all it won't cost much. Remember, this vehicle has low mileage so it's not likely the clutch is worn out unless you have the bad habit of "riding" the clutch.