the problem you have is very common the problem is insufficient flow. When the EGR valve opens it allows ehaust gasses to recirculate through the engine. If the EGR vacuum port is restricted which it probably is, it will cause this concern.
HOW TO FIX
1 : remove the EGR valve
there are 2 holes the larger one is the one that supplies exhaust
flow dont worry about it. the other is a vacuum port this is
where exhaut gases are directed when the EGR valve opens carbon
carbon deposits srick to the walls of the vacuum port and in time
wil restrict flow normally about 30,000 miles
2: Check your local dealer for Intake cleaner ask about BG products
all you will need is the intake cleaner (spray can)
find something to plug the larger hole make sure it will not vibrate
and fall out there wil be slight exhaust pressure on it but not much
just be sure it is plugged real well because if not you may be
suprisied by a flame. Once plugged start the vehicle, spray intake
cleaner into the vacuum port you may have to raise the idle to do
or just open the throttle by hand spray untill the can is empty.
3 : check your EGR valve push the pintle on the bottom be sure it
moves in and out freely if not clean it dont replace the valve once
the pintle moves as it should reinstall the EGR valve disconnect
battery for a few minutes or have code cleared
I assure you if you do this it will take care of your problem I do this often sometimes 3-4 times a day and it always works