I've been chasing the Reduced Engine Power ghost with no codes for about 2 weeks now. I've dug through all of the forum posts on several websites as well as the LMM facebook pages so I won't bore you with all of what they've said. My truck specifically, after the key goes into the ON position, whether it is running or not, will go into REP after about 2-3 minutes. So even if the engine is not running. I have changed the MAF twice, once with an Oriellys maf and once with an AC Delco. I've changed the secondary IAT sensor near the turbo. The accelerator pedal has been changed. The Air filter and fuel filter have been changed. The injector balances are good as well as the rail pressure. I can't locate any wires loose or chafed running to the ECM. I unplugged the ECM and cleaned out all of the connection ports as well as the harness connectors. I'm just out of ideas. The truck has a DPF delete but it's properly tuned with HP tuners and was driven 1500 problem free miles before this issue started up. Just to clarify, even though there are ZERO codes, if I "clear DTCs" with my handheld scanner or HP Tuners it will return to normal for another 2 or 3 minutes before returning to REP mode. Any info would be GREATLY appreciated!