92 Jetta irregular idle

I have a 92 Jetta that when I bought it the air by-pass valve was disconnected. After cleaning and connecting it the car won't idel evenly. It will jump way up and then back down. It will do this about three or four times and then even out. Any ideas? ECU? Can I reset the ECU?

I'd check it to make sure it's really clean inside. Then check to make sure it's working properly (or at least that it checks out electronically). It sounds like it's sticking.

I used carb cleaner on it and before I did that it just idled high when attached. Now it will idle even until you hit the gas. then it goes up and down for three or four times. I have a 92 Taurus that had a bad Air By-Pass valve and it would go up and down all the time. I'm hoping that I don't have to replace anything. The cost of parts, even with my discount at work, is rather high. Thanks for your input.