what could it be

i was out riding one night bike running good come to a stop light no one was around so i hammered on it about 3rd gear it felt like it lost 2 cylinders bogging down bad as i slow down the bike kicks right back in and takes off i opened it up again it bogged back down again no it is spuratic off and on i thought that it might be fuel but i can let it sit and it will still fire and act like it is on 2 cylinders then it will back fire and be back on all 4

What kind of bike.

1978 kz 1000 A2

Original ignition coils,sparkplug wires & sparkplug caps? Time to pitch them and get new.

My bike would be running well--then would lose 2 cylinders... Later, after it cooled down, all four would fire--until the bike got warm... Then it would only run on 2. It ended up being the pickup coils... One would fail under heat after the bike warmed up...
If you are losing cylinders 1 and 4, or 2 and 3, then check your pickup coils...
Grant.