The carb is clean, the plug is new, and has a new air filter. It runs fine but feels 'weak'. I confirmed the weakness when i tried to cut some grass.

I suspect it is the coil. Is there a way to check the coil with a voltmeter or clamp ammeter? what should the readings be for a "healthy" coil?

Coils will not make the engine run weak. It could be a partially sheared flywheel key, low compression, dirty or plugged air filter, or you may still have a carburetor issue.

Running weak could be a lot of things, give us the make and model of your engine.

Sounds like you have done the basics, how old is the mower. I am thinking you have low compression. Do you know the maintenance history.
Dean

i think i have fixed it.

the primer bulb was not working right and somehow that was causing the carb to run lean. therefore it would run but with not much power because it was not getting enough fuel during 'load'.

i'll test it today and report back.