2004 F350 SDW 4X4 Crew xab suoer duty with 6.0 and auto trans.

Truck has new turbo, coolers, etc. 2000 miles ago.
While driving truck I lost throttle while sitting at stop sign, would not throttle up and when it finally did I was able to get it home by not letting it go to idle.
I have an "auto Enginuity scanner and it show that the accelaertor postion sensor is reading. While engine is running it may throttle up and drop back down while holding the accelerator in one position.'
Does not show a code other than
" turbo under boost pressure" which I will approch after this.
ANy help will be appreccitated, I do have a accelllerator pedal assembly on order for $212.00, but if this is not the cause I am out $212.00