This is a great place to get the latest information, products, and news about Corvettes at the home page, and stop here at the forum to share ideas, post questions, and help others.
The rough idle is actually a BIG question. If you do all the regular things, plus, wires, filters, tuning, timing, cap, rotor, vacuum line check, etc, and still have the problems, look very close at the EGR valve. As it goes bad it can cause a world of headaches. Several people here have run into this problem and sometimes only after doing everything else (which most cars need all the tune up stuff anyway) found the problem.
Keep us up to date of what you have done so we can throw our .02 in on the situation.
First of all welcome to the CAC! As has already been said, you've found the right place for Corvette information. We may not all know everything (at least not me anyhow) but no matter what you need to know, someone here will have the answer.
Question: Manual or Automatic? 900 RPM idle is too fast regardless of the answer to this question. If it is an auto, 900 in gear or out? If you slow it down, the roughness will be worse. A good tune up is ALWAYS in order, unless you did one yourself, personally and recently.