Issues with codes, smoke etc..

[2008LMM]

I am getting a 1249 code when under a load on my 02 7.3 Excursion. It has NO tuner or chip. I replaced the wastegate solenoid (the little black thingy with the hoses hooked to it) reccomended by a Ford tech. Didnt fix it. It pours a good amount of black smoke when under a load and I feel it shouldn't being it has no tuner. Also it will make close to 30 lbs of boost when under a load as well. If I am towing and its in high gear if you go up a slight hill you can hear what I call boost "fluttering". I dont know if its trying to release boost and it wont let it or what. I have searched numerous threads on this code and they all seem unfinished. Any help would be appreciated!!