where are the spark plugs for a diamante mitsubishi 97 located?

They are in the cylinder heads, probably alongside or above where the exhaust manifold runners connect to the heads. If you want to find a specialist, here's a directory link for you: https://repairpal.com/mitsubishi-repair-in-lemoyne-pennsylvania

They are located under the engine plastic cover and also located under the intake manifo. You have to remove the manifo in order to remove the back three plugs.