Make sure the vac line to the EGR is not leaking. Ensure the EGR solenoid sees manifold vac (the solenoid is in the passenger fender). Ensure that if the EGR valve has 6" hg of vac applied to it, that it opens. If it does, put a DMM on the position sensor and watch the reading as you manually apply vac to the EGR valve.
It's tough to test an emissions component in it's true dynamic unless you can datalog or see PIDs. However you can see if the puter sends a signal to the solenoid by connecting a test light across the solenoid and then running codes. The puter energizes all the solenoids as part of the test and the test light will flash on and off real quick when it is tested.
I'd do that and go from there. Generally it's a bad vac line, misrouted vac line, position sensor connector that came loose, etc. Easy stuff.
On my 94 mustang ,I unhooked my egr and just built a plate to cover the hole on the intake.I did this so I could use the cheaper 89 style headers.It seems to work fine without the ugly EGR hooked up!!Of course it put the light on, but it only takes a sec to pull the bulb out LOL!!