reduced power mode

[Jer64]

I just finished swapping an 06 L33 and 4L60E into my '64 and finally got to drive my truck, but when I hit the gas pedal, the truck goes into reduced power mode. It is fine when I have it in park or neutral, it idles perfect and rev's perfect, only when I am driving will the truck go into limp mode. The only codes I've gotten are P0650 and U0107. I replaced the throttle body, TPS and double checked all the wires and grounds. Figured the new throttle body and TPS would fix it, but doesn't seem to have an effect.

I recently changed tire sizes from 275/65/15 (which the computer was programmed to) to a 265/35/22 and haven't flashed the computer yet. Is it possible that the difference in OD in the tires is causing the problem? I was going to throw the old wheels and tires on to see, but they're in storage now and haven't been able to get them.....

any thoughts would be appreciated, thanks!