Don't assume clogged tube, even though it is a common egr code problem...

A simple flow test is to apply hand vac to the egr vac port while engine is at idle.. if engine goes lean and attemps to stall/runs rough, the tube is not blocked .
There is a SOV valve that can be at fault and an even more common fault on 104 is the vac line going to the SOV...they crack from heat b/c they are plastic..replace w/rubber. Plus , the egrs on eatrly 104s were known for sticking...there has been a part change..
So, as you can see, an EGR code is not a Tube code, it is a system failure code and requires testing the system...