Dreaded Reduced Engine Power

[Adrian17]

2003 Silverado 6.0L. REP started showing up this past friday. It ised to do it mabey once every 4 months at start up but it started doing it while im on the damn freeway. Today it did it twice in 30 min. Im one for trying to fix things myself so I went online and did some searching well ive tried everything besides replacing sensors and I dont want to start throwing parts at the truck. Any of you guys have any other ideas or should I start buying parts. Appreciate the help.

[Colossus]

Need to get it into a good repair facility that knows these trucks and has the right diagnostic tools/computers to hook up and see what is going on.