My zx was running fine until I kicked it out of gear heading for a stop light. At that point, the engine started reving between 1750 and 2250 rpm continually, up and down. I placed it back into gear, and proceeded through the light, and, the car runs fine. Back to the house, I popped the hood and started checking the throttle linkage for movement during this series of up nad down revs, and, of course, there wasn't. It still continued the up and down reving. The car starts and runs fine otherwise. If I place the car in gear and begin going down the road, and, mash the brake, trying to load the car down, the motor still runs smooth, eventhough it will continue to try to go up to the 2250 rpm and stay there until I kick it out of gear when it will continue to due the 1750-2250 rpm dance. No smoke, no missing.