Hi, My ‘06 Durango ran hot a few days ago....only while idling...it would cool down as I drove. .Took it to the mechanic and I was told that it was my clutch that was causing the problem and replaced it. I just picked up my vehicle from the mechanic and I noticed that the engine is extremely loud now. It seems like it’s lost a little power and the sound seems more like if you drop it to a lower gear sound. I checked the other gears just in case something may have happened and it is in the correct d location. It is shifting and seems to run a little smoother after a few minutes of driving and the faster I go.

I recently had my radiator and my thermostat changed a few months back

its a V6 2WD 356k miles

any suggestion as to the problem ?