94 Corsica 2.2 - surges.....HELP!

After getting up to speed (35-40 MPH or so) then taking my foot off the gas pedal...the car surges as it slows down. When it idles...it is a little rough and occassionally dies...but not every day (usually on rainy days). I have replaced the oxygen sensor so I know it is not that...any suggestions?

hard to say what this is, but here is what I suggest you try before buying any new parts. Check and replace any old cruddy vacuum lines, especially the one going to the MAP sensor if it look old, clean the intake which would include the throttle body and IAC valve. Get a Haynes manual so you do this correctly, the IAC has to cleaned carfully. Clean all carbon out of the throttle body opening, IAC, IAC opening. Have you noticed the check engine light ever coming on? If so, you need to have this scanned, and on your car you should be able to do this easily, should be intructions here on how to do it without special tools, although I have always used a scanner tool, or a cheapo plug in checker on OBD1 cars. You might have a MAP sensor etc. acting up but should be codes setting. The light only needs to light up for a short time, it does not have to stay on to store codes. Maybe even a throttle position sensor. But a vacuum problem will cause problems too so check that all out.