ok, got new rotor, cap, and plug wires on (new plugs were done earlier).

Same symptoms:

starts right up and idles nicely.
when trying to give gas and hold at 1k rpms, it starts to "chug" and gets progressively worse. Letting off the gas and it struggles to get back to idling smooth, but does after a few seconds.

when holding rpms at 2500, it seems to do ok, but letting off gas and it repeats the struggle-to-idle.

I haven't done any throttle body cleaning (saw someone doing something like that when watching a seafoam vid)...could that be it?