Vehicle stalls/ how do you change plugs? on 1994 Oldsmobile Silhouette

My van has been dying while driving and sometimes wont start. The engine turns over but wont start for about 5-10 minutes. It does the same when it stalls while driving. Also how do you replace back 3 spark plugs?

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1 answer
here is some repair info to give you a better picture.

http://bit.ly/mitchell_repair_manuals_online