A bad or dirty EGR can cause stumbling and lack of power. I suggest removing it for a good cleaning (you may be able to rescue it) or replacement. You need a new gasket. Let'* fix one thing at a time, and that'* a known issue at this point.

Theres no difference to oiling and cleaning the egrs on these cars then older ones is there?

I'll be curious to see what you find. I have a post on here and I'm having some of the same symptoms you are but, I'm getting a MAF code. Does your run great till it get'* up to running temp? About the time the termostat opens. Hills are killing me also. I was told I may have vaccum leaks or fuel pumps starting to fail.
Any way keep us posted. At least you didn't blow $138 on a MAF sensor that didn't fix you problem. Good luck

You don't have the same EGR. The cleaning and oiling normally applies to the 90-93 Digital EGR. You have the linear.

You have to remove yours and clean it. Earlier cars do not.