Those engines are known for blowing head gaskets. My son's BroncoII had the same issues, when we pulled the heads we found that one of them was cracked. Take it apart and clean the heads thoroughly. If you don't find any cracks get a new set of gaskets and reassemble it. It will be good experience for you, make sure get a shop manual.

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2003 ranger XL, reg cab, 2.3L, auto, 2wd. 115k miles