96 cougar check engine light

My 96 cougar (3.8 v-6) has a check engine light and hesitates for a few minutes when starting out cold. The codes are 171, 172, and 174 which indicates the oxygen sensors on the right side of the exhaust. Any ideas how to tell if it is the one before or after the catalytic converter?

im sure new spark plugs will eliminate that hesitation,but for the other things i dont know

I had a check engine light going on my 95 cougar for over a year. I had a remanu' engine dropped in and the Engine dudes still didn't understand why it was coming on. So a friend said it might be a cloged cat. I bought and put in with some 89 octane gas, and the light went away after 3 minutes.

Pick it up over at JCWhitney.
http://www.jcwhitney.com/autoparts/ProductDisplay/s-10101/p-3201/c-10101

It goes in the gas tank. Try it with some 89 octane, and see what happens.

I have a 98 dodge Ram... My truck had the check engine light come on and it wouldnt shut off... Luckily my brothers friend has gone thru mechanics school. He brought over his diognostics labtop and within 15 minutes he had found out that my POST converter O2 sensor was bad. Take it in to an autozone or similar store and most of them have diagnostic testors. They'll probably be able to tell you whats wrong.