Ok, so my brother bought and 08 gmc 1ton dulley with 70,000 miles, for his new work truck, his girlfriend has been driving it lately and it goes into limp mode randomly, she turns it off for about 20 minutes or so and it's back up n running again, anyway, my bro is about ready to set it up for work and he can not afford for it to go into limp mode on the job, what I'm wondering is, is there anything he can do to permanently fix this problem? He doesn't seem to care what it costs, just needs a reliable truck, oh and it had two codes when scanned p0401, and p0106, egr delete mabie? I'm not really sure about duramax's, I'm used to working on mining equipment and class8 trucks, anyway, any info would be greatly appreciated