If you are talking about a 3.1L GM engine with the faulty intake manifold gaskets, that GM has recently settled on a lawsuit for, you'll be glad to know that GM (after some considerable legal effort on your own part) will go good for about a 1/3 to 1/4 cost of the repair. You can find all the info you need to make a claim here, and to find out how much you should receive.
Canadian -
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You'll have to read up for yourself because I think on the canadian site, they were only giving us so much time to file a claim. Fortunately, on my '98 Malibu (3.1L, replaced around 225-250k), I knew a retired Chev mechanic who did the repair for around $200. When I need to get the 3.4L done on my '01 Monte Carlo done, I'll probably take it back to the same guy. For those following along, remember that this also applies to the 3.8L engines as well.
Good luck with yours, Sharky