If you look down on the front of the engine it is mounted on a bracket by the water pump pulley and has a tube between it and the passenger side exhaust manifold. If it is clogged your exhaust backpressure valve may be staying closed more than it should, which would cause an abrupt loss of power. Your ebpv could just be stuck closed also. It is the butterfly on the exit of the turbo, you can reach under the turbo and move it, unless its stuck. The rod should normally be shorter when not engaged, it pushes the rod out of the cylinder to activate. Usually if it is stuck you can hear it though.
You might also look for soot on the uppipes and a leak on the pressure side of the turbo, if it blew out a gasket at either one of those places it would cause an abrupt power loss too.
You might also look for soot on the uppipes and a leak on the pressure side of the turbo, if it blew out a gasket at either one of those places it would cause an abrupt power loss too.
