new guy with 6.0 problems

have a 2005 6.0 that i just picked up friday. initial test driving didnt have any problems. but the guy was running one battery in the truck with the other battery just unplugged. bought and installed two brand new batteries. now it started acting kinda doggy and lacking power around 65 mph.but just after you drive the truck for 30 minutes or so. any help and feedback on this problem would be greatly appreciated and thanks in advance

Ficm issue?

Do you have any type of scan gauge or SCT to look at anything with? It could be FICM but you'd need to know the Voltage output on it. If you don't have a scan gauge or SCT heres a video on how to check it.

https://www.youtube.com/watch?v=D8Rlc1el9eg

:whs: It does sound like a FICM problem, but like said above check the voltage to make sure. If you can get it scanned and see P0611 or a bunch of injectors (like all 8) that usually confirms its a FICM problem.