Dead spot?
Is it possible that it could be a tunning issue? the only reason i ruled that out was cause it doesnt do it in 2nd or 3rd gear
This car suspect that the speed-density tune is out of
step with the actual motor breathing (mods like
heads/cam/headers really distort the VE map
from its stock shape). If it comes back on line in
a second and then pulls hard then this is likely.
Driveline vibe or buzzing exhaust can also put
some knock retard on you, though I don't see
why 1st would be worst there.
Borrowing somebody's scan tool should show you
plainly whether it's spark or fuel that drops out,
then you can chase it down from there.

