Now, I plugged the vacuum hose to the EGR valve with a golf tee. Engine runs significantly better. Now, apparently, with the EGR permanently close
Did you even have to plug it? Isn't the EGR valve opened by applying vacuum? It's ordinarily always closed, so I'm assuming the vacuum opens the valve.
Reason I ask is I have a faulty EGR solenoid and was just thinking about doing what you mentioned because I have surging while accelerating and have been wondering if it's the EGR...
After going out and taking a look, it's a real simple system. There's a hose leading to the solenoid from the manifold, there's the two wire electrical connector that activates the solenoid, and then there's the hose coming from the back-side of the solenoid that goes straight to the EGR valve, so if anything it seems you should plug the hose coming off the manifold so you're not losing any vacuum.
This is on my SPFI ea82 though, I haven't looked at the EGR system on my carb'd ea82, though I should, considering it's parked. If it's a similar system (though I doubt it, carb'd ea82 doesn't have an ECU, correct?) I'd just snatch the solenoid off my GL and throw it on the Loyale.
Just my .02.