I have a small issue with my Gen 3 Auto torque converter (I think).
History:
I have a '04 3.2 SWB Auto with about 150 000km on. About 10 000km ago I had to replace the gearbox with a used one due to mechanical failure. This was after a transmission oil change at a dealer (a whole other discussion). When I had the gearbox replaced I had the torque converter overhauled. I have had no major issues since then until this past weekend.
I did a trip down to Bloem from Pretoria. I noticed that the torque converter was being a bit temperamental. It seems to be over-sensitive. Cruising at between 135 and 140Km (120 if the cops ask) the revs initially start out at about 2500Rpm. After one or two hills, the torque converter seems to give up and the revs pick up to 3100Rpm. This obviously hurts my fuel consumption but more importantly, the engine is working overtime. On the way back from Bloem yesterday morning the same scenario occurred, this time however the A/T Temp light also came on. I then pulled over and checked the transmission oil which was clean and at the correct level (indicating no major mechanical wear). I then nursed the car back to Pretoria using the manual setting and not "allowing" the torque converter to kick in by gearing down and driving up the hills in 4th etc.
My questions are:
1. Can the sensitivity of the torque converter be set?
2. Can I trick the converter into running the gearbox in top gear and at minimum revs somehow?
3. Is there perhaps a fault with my torque converter?
4. Is the torque converter issue detrimental to my transmission?
Your expert advice would be greatly appreciated

Also, please criticize any incorrect assumptions I have made
