Ok you may have seen a couple of threads about my ecu possibly being faulty so I'm just going to start from the begining with one thread hoping someone can help me.

Problem:
Engine has massively reduced power from 0 - ~3000 RPM, then kicks off as if it had normal power
Frequently jerks during the reduced power zone - this may be caused by a broken engine mount?

Newest problem:
Idle speed drops when coming to a complete stop and drops to ~500rpm and slowly returns to ~800rpm.

ECU has been suggested as faulty
TPS has been suggested as faulty
I've now been told it could be the distributor or leads missing - However there is no sensation of the engine missing - I know what this feels like and sounds like.

Can confirm:
Catalyic converter is clear
Exhaust has no blockages
Intake system seems clear of any blockages - air filter was cleaned thoughrougly (k&n)

Thoughts anyone?
Specs:
3.5L V6 1999 TH Manual Executive Sedan.
224000km

Update: 1/2/13 1.30pm
The loss of power hasn't occured at all today - possibly due to cooler weather even after the car fully warmed up - was using a different key but I doubt this makes a difference.

When was the timing belt/rear plugs done?
I only have an uneducated opinion but could it be the front or rear rear spark plugs/leads not firing properly from age?

Try as I suggested unpluging ya o3 sensor. If it stops then you can replace it.

Similar symptoms to mine, i replaced leads, plugs, MAF, and then worked out it was the oxy sensor

Pickles: Timing belt was done at around 190,000, rear plugs were done Either last service or service before.

Rush - The O2 sensor, is that litterally under the carpet or under the car into the exhaust - Having trouble finding that one.

Pickles: Timing belt was done at around 190,000, rear plugs were done Either last service or service before.

Rush - The O2 sensor, is that litterally under the carpet or under the car into the exhaust - Having trouble finding that one.

It runs into the exhaust but the plug is in the passenger footwell in the centre. Its white with 4 wires. Look in the workshop manual if u need??

Righto I'll have another check - also have updated first post with new info