when accelerating hard i get to 3500rpm it losses power then it gets to about 4200rpm
then it bursts it to life jolts you back slightly which feels great but why the flat spot.
Usual is sparks, spark leads,distributer, crack in accordian that connects the maf to the inlet throttle bodie.
Could be a range of other sensors but these are usual faults
if the first set of faults revels nothing try pulling codes from ecu.