I have a 91 - 300\e with an EGR acting up. What I do in the same situation (If the EGR is the same)is to spray a little bit of WD-40 and with the access to the shaft (careful with the diaphragm)move it a little bit with a flat screwdriver. That unsticks the EGR shaft and clears the problem. It has worked wioth me many times and I clear the problem every time.
Let us know.
AdamR
91-300E -164K