Glenn,
Things like a dirty air filter and bad MAF sensor do cause jerky progress at low revs.
However, Arthur and I have been moaning about the learning mode of the gearbox for years.
When you have been driving smoothly for a while, like on a carriageway, long journey etc, the TCU for the tranny "learns" your driving behaviour, and thinks you want going ultra-smoothly all the time.
So it will stay in a high gear and try to accelerate using the torque, which is too slow for the situations you mentioned.
I now keep mine in POWER mode all the time, mine having JDM electronics. You are dead right to keep in three around town, and for filtering into fast lanes and such.
Another trick I learned which will work for you; POWER mode comes on when you demand fast acceleration. The box switches it on based on
how fast you depress the throttle and what speed you are doing at the time. In anticipation of an overtake, have it in third or second, give the throttle a rapid blip with your foot, and come back to the throttle position you were on. It lights up the power light for a while, and then when you ask the question with the green light lit, it GOES.
Practise it on a quiet carriageway as you trickle along, when you have learned the exact speed and distance to blip the pedal, you can engage POWER every time.
Joe