Very interesting details, I'm pretty sure my car is more on the simple side of things since the mid 90s Toyota seem to have that factor, and the corolla is more of a base model type of a car. So I'm pretty sure when I feel/see the lockup, it is on fully or off fully.
The EGR related effects could be what is going on, the car does have 230k miles and similar models have EGR clogging issues at lower miles (97-2001 camry) which I have seen first hand in 2 of 3 cars, 3rd being only 126k miles (no issues), other two are around 180k (rise and lower of idle rpm, one throws the EGR code).
I'm not sure how soon I can investigate this further since I'm still on shift at work and I just had a large load of computers/printers come in (recycle them as a hobby/ side income). With an estimated 500 pound load (3 servers, 6 desktops, and a few printers/printer parts) with the trunk open I averaged 38mpg @ ~45mph
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I think I'm going to need to learn about the x-gauge feature a bit more for my car, the egr details would be interesting to see.
For the smart phone app thing, I don't own a smart phone, I use a $20/3 months prepaid since I never use it. I did look into running similar software on a laptop though.
For a few more IGN readings...
Idel when cold - 22
Idle when fully warmed up - 11-12
While under a larger load than normal it dropped in the 33-36 range on hills, and steady speed it kept around 37 more with 39s here and there.
I found I can stay in the higher mpg "mode" when my MAP sensor is at 7 or lower, to maintain 45mph it needs to run at around 6.6-6.9 which is hard to keep in that range, but once there I can basically freeze my foot there and be good to go till hills/stops. Normal 45mph the MAP sensor is 8-8.3, HPR goes to about 14hp when saving gas, 18 when it seems to waste it.