Experiencing Torque Converter Issues

[invader166]

It's my turn to post my griefs/problems for your dissection:

I have a 2009 Yaris AT that I feel is starting to exhibit problems with it's torque converter.
I'm experiencing occasional slippage under heavy acceleration, lower acceleration speed, (did a comparison between my car and another stock AT Yaris and mine had some trouble keeping up; had to rev the engine more I feel) and shuddering that comes and goes at iddle speed.
Also checked the transmission fluid dipstick and found some black-powdery contaminants on the stick. Fluid colour is a slightly dark red.
The car has just over 65,000km and I don't recall if the previous owner ever did a transmission oil change.
Should I just start with changing the ATF and have someone take a look at it?
I have an oil change scheduled in a few days so that would be a good time to do it.