92 Plymouth/Chrysler Voyager SE 3.3 - A604 Tranny "Binding"? but no limp mode?

Hi, The Van has done 329,000 Km, i purchased it 8 years ago with 150,000km.
The tranny was refurbished as i found a sticker indicating a rebuild.I
replaced the fluid and filter at 320,000km and recently reversed the
input&output lines to&from the aux cooler. We live in a warm climate and
this has improved the overheating that happened occasionally.

I basically travel 25km down to work at sea level in the morning and return
uphill in the afternoon. The last hill i negotiate is very steep (just had
the famous comrades marathon- runners walk up there) Halfway up it feels as
if the tranny is binding, if i take my foot off the gas it relaxes, when i
step on the accelerator it binds again and i basically have to slow right
down and go up the hill in 1st gear or stop to make a fresh start. At times
it makes a clunk-clunk noise (very scray-like something could break-but no
real evidence of broken planetary etc)Another option is to really floor the
accelerator, let it kick-down and keep the revs (RPM) high. At the top of
the hill it seems to settle again and behaves unless lots of traffic or very
warm day.

I am planning to replace the ATF+3 again, with filter and in-out sensors.
Also thinking of stripping and use rebuild kit to replace seals etc.

Any idea what is happening? I don't think our dealership has the equipment
to pull codes as the chrysler voyager only landed here in RSA in approx1997.
I am not convinced it is only heat related, the ATF still looks "reddish"
but has taken some punishment. Is a service/rebuild necessary? The ATF over
here is R44.95 a quart and i need to be carefull how i sort this problem
out.
Any advice will be greatly appreciated.

 

Similar problem same car. Today had shop "fix" it they replaced "solenoid
pack" drove home from shop 80 miles away, same problem occurred, had to
pull over and start again 3 times. $125.

Don't know what is wrong. Transmission rebuilt two years ago.

Mike