[Joust]

I have this exact same problem.
i notice it after the van has driven over 30min or so.
when its cold i never see this problem. once it warms up it is there. BTW i put the largest tranny oil cooler i could find onto this vehicle when i bought it. my lsat van went through three trannies then i junked it.
Is this for sure the problem? What would a repair like that go for?