When you say "they", is this a dealer or a private shop? Dealers have some pretty high tech diagnostic equipment that can usually pinpoint the problem, while the independent shops have generic scanners that might not get to the root of the problem. Sounds like you've spent a lot of money with no real solution so far. And the 97 was a poor year for S10s in general. Hate to see you having this much trouble. I'd suggest a trip to a reputable dealer - if there is one in your area.