Engine Racing/High Idle

For the past 2 weeks. My 2001 Saturn SL, manual transmission, 5-speed, 4 cylinder (80,000 miles) idles extremely high upon starting, remains on a high idle while driving, and when shifting gears, it often goes past the 3 rpm indicator. The lower the gear, the more the car races. When I put it in neutral, it will idle high for a few moments and then drop below the 1 rpm indicator. However, as soon as I shift into 1st or 2nd gear, it begins racing again until I get to 4th or 5th gear, at which point it will "drop" but not go to 1 or below 1 rpm; that only occurs when I place it in neutral. Is it a simple matter of getting a tune up or is something more serious "lurking" around the bend? Thanks!