whats it doing at 3000rpm
losing power getting none dying
flat spots, jerkin around, back firing
check ur timing, points, spark plugs and leads, coil, ballast resistor.
check ur carbi too could be blocked shit got sucked into it
check ur float needle and seat in the carbi to and fuel pump could not be getting enof fuel to it,
lots of reasons why
hope this helps
Jai