This cooler is the one that I installed on my 2003 Sienna.
http://www.bulkpart.com/Merchant2/me...e=tru-cool-lpd

I do not know what is causing the problem you are having.
I would advise that you have the codes read.....using a OBDII code reader or stopping at a auto parts store, like AutoZone, where they will read your codes for you for free.
Make SURE to ask for and write down the actual numeric code that they get.
On my 1996 Windstar, I had the Vechicle Speed Sensor go bad and cause the transmission to not shift correctly.
On newer Windstars, the Transmission Range Sensor, also known as Neutral Safety Switch, is a common item to fail.

Hi, i'm from Mexico, so i gonna try my poor english. I just purchased an 2003 windstar lx 95000 milies on it, after sell my 96 windstar gl. I just traveled from Des Moines, Ia to El Paso, Tx, and everything good, even with 110 degrees on Oklahoma. Ok, the point is, when arrived to El Paso, on a stop ligth, i feel like the transmission was shifting, and once the green ligth came on, i feel like the gears are not shifting right. Before the trip, I changed the fluid transmision filter and fluid ( just the pan oil with mercon V fluid). Please help me with this issue, I love the windstar but I'm affroid to have a bad transmission. I'm planing to install a auxiliar transmission fluid cooler, could you advice me wich one buy?