I have also searched many times.
Problem is most of the people having these problems don't post what the solution to their problems were

Trans is a 4 speed tip in 1995 GPX.
Symptoms:
Drives fine for 10 mins or so, then starts to "slip" and hesitate on changing gears.
Gets worse over couple of mins, eventually slamming into limp mode. Car really dies hard, like it's dropping back into first gear at bout 30 kays, then goes into the dreaded 3rd gear limp mode.
Still got plenty of drive considering it's in 3rd gear, at 60 kays it's quite normal to drive (Minus 1st, 2nd and 4th gears...).
Checked error codes on trans ECU. Getting code 42: 2nd gear out of spec.
I have changed the oil to genuine Mitsi fluid of the correct rating. Oil that came out was black as night, but had no burnt smell. Suspect that the car yard I bought the car from didn't service the trans as agreed to at the time of sale

(Had another problem just after I bought the car and found out their mechanic was a gibbon...) So chances are it's very old trans fluid.
Test drive-
Still same problem.
Read a few threads saying bout the input shaft speed sensors being suspect, so bought a S/H sensor (Didn't want to wait a week to have a new one one shipped from oversees or be analy raped for local mitsi dealer prices) to check if this was the problem.
Plan was, if it fixed it, then buy a new one...
After it was fitted, still the same problem...
Took it to a trans mechanic to look at who, of course, want to rebuild the box. ($2000 to $2500 estimated) However these guys have never done an FTO before and apart from saying it's "the same box as lancers have" and mentioning plates that can wear inside and pumps and solenoids that can fail, couldn't give me a straight answer on what it could be.
So...
I'm assuming (hoping) it's not a torque converter as oil didn't smell burnt, still got plenty of drive, and most people with TC problems don't seem to get error codes.
Points more towards sensor problems, but I've only found people with input shaft speed sensor problems, none with output side probs. Figured the chances of getting another lemon input sensor S/H were pretty slim.
Questions:
Has anyone had the same symptoms and if so, what fixed the problem?
Has anyone had an output shaft sensor pack up on them?
Does anyone know of reputable trans places in Adelaide with experience working on FTOs?
Any other info would be greatly appreciated.
Cheers.