My guess about Ken Dixon's problem is the torque converter.
Is anyone familiar with a surging A6 4.2 L engine while under light accelleration? Mine surges about 100 - 120 rpms under light accelleration but doesn't do it while on cruise control. Any thoughts as to what me be going wrong? I'm on my second 4.2 L engine in this car and the same thing is occuring with the second engine - hopefully it's something with the fuel pump system. Thanks - Ken Dixon