As far as the pair valve delete, I'm pretty sure I used EGR gaskets on both of mine. I know I machined the two cover plates from the same template. It's been a long time but I'm pretty sure that's how I did it. Don't quote me on that but take you some measurements and see if that won't work.

As far as the engine running fine at idle but feels like it's under a load in gear, have you tried letting it idle while you pull off your plug wires one at a time and listen for a change in RPM? When I first got mine it was running anything but right. The AFM had been fooled with like you're talking about so I replaced it. After that it seemed to run just like you are describing. I was even getting an O2 sensor light. I replaced the O2 and the light went out but it still ran like "you know what" in gear while perfect at idle. When I started pulling my plug wires off I noticed no change in RPM when I pulled off three of the wires. I finally settled on three injectors as the problem and replaced all of them. When I started it back up and took it for a drive, it felt great. Not suggesting that that's what your issue is but it's a cheap and easy trick that might shed a little light on your situation.

 

Might have to give that a try....
I know that i have pulled the number 6 plug while it was idling just to be sure cause that plug looked a a lil dirtier than the others when i changed them and the idle changed (just like i pulled a plug wire lol)
Might aught try it on the others.....
I have a set of egr gaskets that should be here today and im gunna tackle that project this weekend... might order another set they are cheap enough aswell....
I know that if i pull the intake plenum im gunna need to replace all the garbage under it cause i done want to have to do it again lol so i might just order a set of injectors to do while im in there aswell