You will have a terrible time checking the EGR on an 88 300e of any kind, as they don't have one.

Get a set of manuals on CD (they are available from several sources). Haynes manuals are pretty much useless beyond changing oil, belt, or brake pads, and may not even help much there.

What makes you think the (non-existent) EGR is stuck open?

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!