Mitsu trans? slipping when hot

I have 2000 mitsubishi montero sport 2wd that seems to “chug” when the tranny gets up to full operating temp. If it’s cold, it’s fine. And it only chugs going up hills. I live in tn so hills are unavoidable. Tranny fluid level is fine. It has 200k+ miles so if rebuilding the tranny is the only option I’m ok with that too. Thanks for the help in advance.

Then I Take It That You’ve Got An Automatic Transmission As Opposed To A Manual ? Let’s Start With The Basics.

Please explain why you’ve narrowed it down to the transmission as being the “chugger” as opposed to say, the engine.


Automatic, yes sorry to have left that out. If I start up a hill when I know it’s going to do it I can drop the gears down and make it up just fine. Once I leave it in drive…CHUG. The engine seems to be ok idles fine and runs fine otherwise. Ideas as to why you think it might be the engine? I replaced the spark plugs and wires last year(expensive).