I don't think those IMRC valves cost that much. Probably not a bad idea to replace it. It should have a small 'R' on it to designate it is the right IMRC, the left one has a small 'L' stamped on it's mounting bracket (usually). If it failed before it will most likely fail again. In you intake duct by your air cleaner is your MAF sensor housing. The sensor itself is usually removable on Fords with a tamper-proof Torx socket (tamper-proof Torx screws are like regular Torx screws but with a nub in the center so a regular Torx socket won't fit). If you remove the sensor itself from the housing it is cleanable with regular carb cleaner and we usually blow them dry with an air gun after cleaning. A clean MAF will do wonders for an engine. Make sure you have a new PCV valve in her to witch will help reduce blow-by from getting into the intake tubing. I would still consider removing that upper intake plenum, you should be able to do it with a basic manual and hand tools. This will allow you to examine the lower intake ports and check for those EGR passages, do a little cleaning, and replace the plenum to lower intake gasket which are notorious for causing vacuum leaks when they get old. You should be able to remove the upper plenum with the throttle body still attached to the upper plenum on most cars, you just need to disconnect any linkage, vacuum hoses, etc.. Keep us informed.