Random/intermittent high idle and exceleration

[bags1010]

Customers truck is a 2009 6.4 with SCT and DPF delete with sensors in exhaust. Truck randomly goes to 1500 or higher and never exactly the same rpm. Sometimes just sitting in parking lot while in park, sometimes when going from park to drive, and sometimes while accelerating or driving. Tunes have been checked and updated, acclerator pedal has been switched with one from a working truck, and no codes are ever displayed. I have been told to replace the sensors in exhaust and also to check wiring from pedal. Problem is that its so random, its may take 3 days to do it again, but does it 20 times that day. Any ideas on a cause/solution?