to check the egr, remove it, flip it over and secure it with the gasket surface level. now fill one of the two chambers you see with solvent. it should hold the solvent in the port for awhile. if it starts to fill the other port then it is leaking and will cause exhaust to leak into the intake manifold when it is supposed to be closed. this will cause the stall and hard start, poor fuel mileage etc. they will sometimes stick in the open position if the vehicle is not used for awhile and then taken out for a run, especially when you coast down a hill or go from high speed roads to a low speed road. that is when the valve is supposed to open and burn up some of the unburned exhaust gasses. the problem is that the valve can open further than it normally is used to, and then stick there. or the valve can just plain be worn out.
check it, the solvent shouldn't go anywhere.if it does the valve is toast and you are on borrowed time if you clean it and stuff it back on.