SC400 auto: schizoid shifting, but only for first 5 miles?

[the toecutter]

got a weird problem cropping up (i'd like to throttle who ever it was that did this swap). every day i start up the unit and it usually gets warmed up to about 160F (idling down) by the time i'm ready to go. i get rolling, and it goes out-to-lunch not being able to decide whether to be in fourth/overdrive or second, or flutter like mad between gears. it will get stuck in third or fourth/od and refuses to downshift no matter what the throttle. or it might decide to get stuck in second, and refuse to upshift. or when it flutters between gears, i can hear what i assume is a solenoid going "clikety-click" with every gear change. but here's the weird bit, only for the first five miles or so. after that, it gets its act together and drives like a dream for the rest of the day. until tomorrow. sometimes it will do it (but not as badly) at the end of the day if it has been sitting for a long time.

my mechanic and his auto-transmission guy swore up and down that it was the shift solenoids going out, and that should fix it up. well, that didn't work. and here's the other part of my problem: the person who wired this swap saw fit to not include a cel. and after testing at the engine plug, and the ecu plug, there is no cel signal to begin with. so i can't get any fault codes at the moment.

could this be the throttle position sensor causing this condition? ecu fault? i have no cel signal, which suggests to me that there already is something wrong with it.