Error 9?

My friends 94 protege dx started acting weird recently, at some random time while driving the "check engine" light will flash and then the car floods itself at high rpm and when he takes his foot off the gas it idles at around 1500rpm (enough to pull itself along in 1st 2nd or 3rd)

We checked for an error code and came up with error 9, water thermosensor? What do we need to replace? Is it anything he can use from his parts car?

Thanks, Justin
 
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