Dodge: Grand Caravan power loss, dodge grand caravan, loss occured

Question
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Followup To
Question -
1997 Dodge Grand Caravan 3.3, 130,000 miles (or so).  While driving on cruise at about 70mph, the power dropped, engine revved and then the engine sounded like it was operating in overdrive - a vacuum sound under the hood.  This occured after being on the highway for about 350 miles.  Also, about 2 weeks ago a "swish swish" sound started from the belt area.  I could hear it when stopped in traffic, but not while moving (though I think it was still there).  When this power loss occured, the "swish swish" noise was gone.  Looking under the hood, all I found was the oil was 2 quarts low.  As I limped the vehicle home, it would get to about 45 mph at 3500 rpms.  Anything more sounded like it was working way to hard.  
Appreciate your thoughts and repair suggestions.  (yes, added the 2 quarts of oil).
Answer -
Neil,
Have you checked the catalytic converter?If the converter is coming apart it will make this exact sound,and will cause a tremendous power loss.It's not oil related.What happens is the converter breaks apart inside the exhaust and restricts the exhaust from exiting the vehicle.Let me know.

Would a catalytic converter problem include symptoms like the engine trying to find a gear?  (sometimes not catching at all and engine revving; and sometimes catching with force to push you back in your seat)?  And of course the check engine light is on, steady.

Answer
More than likely if the converter was stopped up you would have no power,If the engine light is on take it to AutoZone and let them scan it for you,this will tell you if it is a sensor problem.Although i would not hesitate having the converter checked.It is possible that it crumbled enough to just partially block the exhaust.I just replaced mine on my wifes Dodge Ram.She told me it lost all power,when i got home from work i started the engine and could hear a swishing sound from under the truck,i put my hand over the exhaust and could not feel the exhaust coming from the pipe.Another way to tell is to get under the van and hit the converter with your hand if it sounds like something is loose inside then the converter is broken.Another thing is a vacuum line could have come loose from the intake,when checking for a vacuum leak look close because it could be just dry rotted and cracked in the middle of the line.There is a lot of things it could be.But start by getting the code read by AutoZone if at all possible.I know this is a lot to check..sorry i can't diagnose it hands on for you.