Re: More Help
I don't think the shake is EGR related. You can bypass the EGR, but it's better replacing the unit for legality purposes. I've personally never had an EGR fail, so I can't tell you what the symptoms were, even though I'm sure it's a bit different for each vehicle.
I'd look more into the driveline. You'll have to try a bit more to narrow down the source of the shake. First thing (you can do this yourself) is to rotate the tires. An out of balance tire can cause a shake, a bad wheelbearing can also cause a shake, and some steering play depending on how it was wearing. Front end suspension components should be given a once over to make sure nothings broken, etc.
As the shake happens at two different speed ranges, my other 'guess' here is that your driveshaft is out of round. You'll have to get a shop to check for this. It can be common on more abused vehicles, as if driven over rough terrain, or debris, things can dent or damage the driveshaft giving off a pulsing sensation at different speeds (depending on engine and road speed, not just by the gear the truck is in at any given time).
If you pop the hood and the engine itself is shaking, then I'd recommend the obvious from a maintenance standpoint, from an engine code scanning to a full tune up.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!