Cm870 throttle issue

[Hambone]

Had the truck tuned and removed goverment BS, Been having boost issues so i have replaced cac,turbo accuator,exhaust manifold gasket ,turbo air supply control and boost sensor... Truck is running ok but if you idle truck up to 1500rpm it'll sit there a minute then idle down. No codes but if you put your foot down and hold it to 2000rpm truck will flucuate between 2000 and 1800,let off the pedal a little say 1900/1950 doesn't seem to fluctuate.... no codes but do y'all think it may be accelerator pedal ?