Auto trouble

I cant work out what happened on my trip with the auto. It was fine for the first week and then we were climbing a slow grade for about 15 minutes on a gravel track when I noticed it was lugging along at very low revs. Tried to get it to kick down and then was when I noticed that the engine temp had got up to 125*C. But since then it keeps pumping fluid out of the kick down cable at slow speeds only even when not under any load which means I get trans fluid on the intake which then spills onto my headers. I found that the fuel filter that I have on top of the vent hose was full of fluid too. Have taken that off even though it has been fine for the last 4 years like that and now have to catch the fluid in a Coke can. The fluid level is right but it still happens. I dropped the pan today and the fluid is nice and clean as I had serviced it the day before we left. No sign of burnt fluid either. Got me stumped as have not changed coolers or anything. Did have the radiator out just before we left too and lines are hooked back into it?

Checked my FSM for a few hints--
1-breather vent in oil pump blocked
2- Cooler lines or aux cooler plugged
3- Too full of fluid
Most of these items you have already checked.Not sure about the oil pump vent or where its located.
The throttle cable has an internal seal,that may have failed.but the only way to get fluid out of it is with internal pressure in the case as it only works against a cam to the valve body no direct fluid pressure.
FSM suggests a reverse flush of the cooler and lines with mineral spirts,then blow out excess spirits and run atf thru before attaching lines.
A DRB tool can be used to scan for any codes in the electronics of the tranny.
HTH
Wayne

Thankyou. I will check the cooler lines today in case when the radiator was repaired just before we left that they didn't let some solder or other rubbish get into the cooler inside the tank when working on it or when leak testing it afterwards.