Trans rebuilt, now it overheats

I have a 1997 Grand Caravan with 190,000 miles, I just had the transmission rebuilt.
I have always had an external trans cooler and temperature gauge on this because we use to tow a camper. The average trans temp has always been around 150 and might make it to 210 if we towed a camper in the mountains.
Now after the rebuild it is averaging 180 when running on the highway and can get up to 230 in the city, this is without the camper.
The place where I had the trans rebuilt said it is over heating because the cooling lines run through the radiator and the external cooler. They claim it should not run through both they also claim the radiator is transferring heat to the trans fluid and I should disconnect it from the radiator and only run it through external cooler.
Could this be true?
What else might I look for?

On another note I have always been told to use ATF+3 7176 transmission fluid, they say I don't need to worry about this anymore. Could this also be true.

Your thoughts and advice on the overheating problem will be greatly appreciated,

I have a 1997 Grand Caravan with 190,000 miles, I just had the transmission rebuilt.
I have always had an external trans cooler and temperature gauge on this because we use to tow a camper. The average trans temp has always been around 150 and might make it to 210 if we towed a camper in the mountains.
Now after the rebuild it is averaging 180 when running on the highway and can get up to 230 in the city, this is without the camper.
The place where I had the trans rebuilt said it is over heating because the cooling lines run through the radiator and the external cooler. They claim it should not run through both they also claim the radiator is transferring heat to the trans fluid and I should disconnect it from the radiator and only run it through external cooler.
Could this be true?
What else might I look for?

On another note I have always been told to use ATF+3 7176 transmission fluid, they say I don't need to worry about this anymore. Could this also be true.

Your thoughts and advice on the overheating problem will be greatly appreciated,

What was the reason for rebuild??? Did the shop flush the tranny lines and coolers to get rid of any contaminates from the failed tranny??

Starter van after a short stop and when I put it in gear it made a god awful grinding noise. Both forward and reverse gears were gone.
They said the planetary gears had failed.
I do believe they did flush it, before he started he stated he would replace the external cooler if he found to much contamination, just to be sure. The old cooler is still on there, so I am assuming they flushed it and it was clean.

Starter van after a short stop and when I put it in gear it made a god awful grinding noise. Both forward and reverse gears were gone.
They said the planetary gears had failed.
I do believe they did flush it, before he started he stated he would replace the external cooler if he found to much contamination, just to be sure. The old cooler is still on there, so I am assuming they flushed it and it was clean.

Was a rebuilt or new torque converter installed??

Yes, the receipt says
1, "Custom rebuilt Chry A604 transaxle Assy"
1, "rebuilt exchange torque converter"
1, "New D.S CV axle"

I also just pulled the cooling line off the trans coming from the cooler and ran the engine in drive and it pumped out about a quart of fluid in just a few seconds.

Last I heard about AFT+3 is that they don't make it anymore so Chrysler said you should now use ATF+4. Based on what I've read in this forum I won't use anything else but AFT+4.

And the shop's excuse that the radiator is transferring heat to the tranny fluid is baloney in my opinion. First of all it wasn't a problem before, and second, it was designed to run through the rad so it can cool off, not get even hotter. If that was the problem it wouldn't be run through the rad in the first place.