Hello i expirince a lot trouble with this problem.
17953 Throttle Valve Controller Malfunction
Its caused only under FT acceleration and over 4500rpm. As simpoms, if have meassurements on channel 4, have voltage droping(some times uder 11v)
At normal driving condition voltage is normal 13.5-14v.
If restart engine no problem at all, can make TBA and can reving engine at 7000rm from idle without problem(if car no accelarate). But when accelaration at driving problem occurs.
Try other TB, other ECU, new parallel harness for TB.
Try too:
remove 4 oxygen sensor
remove MAF
Remove mounting acutator, intake actuator, evap actuator, intake camshaft valve and etc. With no result.
Next is to change full engine harness and ECU with new oxygen sensors(here there with fuse originaly).
Any suggest will be helpfull, im in bit block with this problem.

http://nefariousmotorsports.com/forum/index.php?topic=5295.0title=

Please read stickies before posting.

So after more research, found it have voltage drop of 12v line of J271 over 4500rpm, which make to throttle body do go over limit. Even to bypass J271/Motronic current supply relay/ have same story.
What can cause for voltage drop, under 4500 rpm have no problem at all. Keep solid voltage +-0.1v.
Im check all wiring, try different coil and so on. Try to disconect almost everything. Still hit the rock with this problem.