GQ auto probs

hey ive been having some problems with my auto.

it started with the occacional simple shudder on take off. then it would constantly slip and rev its arse off whenever id accelerate. I checked the fluid and it was filthy so I gave it a service today. got about 5Lts out of it and changed the filter and gasket. drove it for about 10mins and it seemed a little better but not 100% and then it decided it didn't like 3rd gear and now it wont change up from 2nd. the fluid is filthy again.
I first noticed it not too long after driving through a lot of water and mud at work one day.

any suggestions?

you'll need to flush it all out mate, if its a TB42 then they hold around 10ltrs

Sounds like you may have sucked in water/mud through the gearbox breather.

I'd take a guess no matter how many flushes you do, the gearbox is farked and its in need of a rebuild :(

What do you mean by filthy? did it look like it had water in the oil? Any metal fragments???

2 me it sounds like the clutch packs are worn at best.

Don't forget the torque converter holds a few litres of oil and if you only emptied the pan and restarted the car the dirty oil left in the torque converter will make the new oil look filthy again. So a few flushed will be needed before it looks 100% clean.