I think a little technical background might help. The electronic throttle consists basically of an accelerator position sensor (potentiometer), a control unit, and a throttle actuator (ETA) -- a motor that moves the throttle valve. This system is seperate from the ABS/ASR system, though the two communicate.

The ETA reports its position to the controller. While the ignition is on the throttle control unit monitors the quality of that signal and the quality of the signal it receives from the accelerator position sensor. If it detects a problem in either, then it will switch-off the ETA and cause the car to go to Limp Mode.

From the above description you may see that a failing ETA is an electronic throttle problem basically not related to ASR. It may appear to the driver that it is an ASR problem, because when the ETA switches-off the ASR recognizes the problem and turns-on its MIL.

So, disabling ASR will not cure Limp Mode in the case of a bad ETA, but it may improve performance under other circumstances. The ASR controller can signal the throttle controller to override the driver and reduce the opening of the throttle when it detects wheel-spin. A malfunction in the ASR could cause it to signal throttle rduction inappropriately, and in this case disabling ASR would be beneficial.