4AGE EGR system maintenance?

[Red]

First off, a healthy and safe New Years to you all who will be going into 2007 ahead of the US.<G>

I'm trying to do some long-term maintenance on my GTS, looking to see if I can tweak the gas mileage up a bit. All the obvious things are done (like a major tuneup, tire pressure) and that leaves me wondering about the EGR system. I see notes in the shop manual to clean out carbon deposits and clean the EGR vent filters during replacement.

Has anyone done this, and if the EGR system is working (as mine is) does this make any significant difference? 95,000 miles on the car.

Also wondering why the 86/87 models are rated several mpg higher than the 85 model, aside from the ECUs there appear to be no significant differences in the US models, at least, none that anyone has been able to pin down. The difference in tire size is almost nill, the intake and exhaust are IIRC the same, the combustion chamber design also the same. But somehow, the cars showed a 10% highway mileage increase--and the test standards didn't change, either.