Weird stumble when at WOT

Hey guys,

I am getting a weird stumble from my 1990 GT when I mash down the
pedal at WOT. It feels like all of a sudden I am running out of gas
or just loosing power. I have checked all the vacuum lines and I am
not sure what else could be causing this. Here are the modifications
I have done recently which one of has to have caused this:

Cobra upper and lower intake manifold (w/spacer)
Shorty headers
Radiator
Water pump
Fan w/clutch and shroud
cap and rotor
wires
alternator (upgrade to 130A)
Ram air hood

If anyone has any idea what could be causing this I would appreciate
this, it's not fun when your mustang won't get up and go when you want
it to. Thanks for the help guys.

Sean