Fatblazer

I have over 7,000 miles on my 05 GT Stang, When I am cruising in 4th at high rpm's roughly 3500 after a downshift from 5th, I noticed when I punch the gas, around 4000 RPM the car will choke, as if the fuel line was interrupted. Doesn't feel like the tranny at all, and it is only in 4th gear, I have tested the same situation in all gears but having no problem execpt in 4th. Anyone having this or a similar problem? Thanks, Peter T.