Yeah, the spring inside the EGR valve on my 200 broke once. It would sometimes stick open, causing rough or no idle. I fought the dumb thing for months before figuring it out. When it would stay open, the thing would die at every stop. Then, just as suddenly, it would be OK again.
Replacing the valve introduced a different problem: the EGR valves come in 3 varieties for the 200. Each one has a different spring rate and diaphragm size. When I replaced mine with the only one I could still get new, it had a larger diaphragm, which makes it open sooner than it otherwise would. This particular type requires that the venturi vacuum be directly connected to the valve (through the heated port vacuum switch), rather than being driven by the vacuum amplifier thru a WOT vacuum switch, which is in turn connected to venturi vacuum.
The result was that the car would start good off the line, then fall flat on its face when the EGR valve opened suddenly (and too soon). The gases thru the valve can actually be heard inside the car when the valve opens. Changing the connection to run from the venturi vacuum (again, thru the PVS heated valve) lets the valve open slowly, which stops that "dying in its tracks" feeling at launch. The valve should open above 1600 RPM on brisk acceleration, not at all on WOT acceleration, and partially at about 1350-1500 RPM in steady, level cruise.
Oh- and, if you have EGR and disconnect it, you will need to reduce the static timing by about 2 degrees and change the dizzy vacuum advance to run from port vacuum to compensate for the over-richness of the carb's EGR calibration. Chances are, you have no vacuum advance at all in the stock configuration, except during cold startup phase. Then the vacuum is stopped during normal run temps, to become manifold vacuum if you overheat (that's supposed to speed up the engine and cool it down a little).
