First impression to me is way too much fuel. If its bucking under throttle and when you let up it wants to accelerate, that to me means when you let off the gas the air:fuel is actually going towards something it can use instead of just raw fuel. Have someone drive behind you when you go WOT and see if its backfiring/blowing black smoke out.

Also, did this problem just arise or has it been like this since it was turbocharged?