i'm not sure about yours but i had a 95 grand am that had a very similiar problem, i talked to a mechanic at the dealer and he said that there would be a vacumn line (gray) between the headlight and battery on the drivers side that would be shafed and leaking. he was right once i spliced it, it was fixed i don't know if the lines on a s10 are in the same place but someone at the dealer will probly know good luck