My expo has a large lack of power after coming out of a hard tune like coming off an on ramp. drives ok normally but misses and bucks after the hard turn onto the interstate. Fuel system is ok with no water in tank
Just a guess but suspect something is up with the fuel pump. Either a wire has a momentary loss of power due to a poor electrical connection or the pickup tube shifts position.
Does the check-engine light come on? Have you checked for codes even if it doesn’t?