I had a similar problem that seemed to resolve when I cleaned out the EGR. If the thing hangs open at closed throttle it'll drown the idle with excess exhaust air just the same as if you pushed the diaphragm on the EGR. I found that not only was the EGR port on my 2.6 loaded with carbon, so was the back pressure tube that goes into the bottom port of the transducer. I had to take that tube off and clear the hole with a small drill bit. Keep in mind that the operation of the EGR is cut off on a cold start by the thermal valve in the underside of the intake manifold. If that valve has failed in the open position that will allow the EGR to work when the engine is too cold to accomodate the exhaust gas and choke your engine.