My experience is all with the version of the engine in Chrysler K based front wheel drive vehicles.
Well, the 3.0L V6's biggest issue is oil burning. Otherwise it's a good engine with relatively little issue. The timing belt and water pump service isn't fun but it's doable. My LeBaron convertible runs great still and has never had the engine apart for anything besides it's first tune up and timing service... at 152,000 miles haha. I used to have a Plymouth Voyager that had over 300,000 miles on it before it had an injector fault that caused it to blow a head gasket. That engine was all original besides some seals and consumables. They're great engines when in the Chryslers if you don't mind poisoning people behind you a bit hahaha.
Now, as for the ones in actual Mitsubishis, I don't know all the differences but I would assume it's the same story as long as you're not talking about finicky turbo charged stuff. Those are an absolute nightmare under the hood.