another P0741 code question

[pardeevibe]

Hello, I'm new to the forum, having just purchased a 2005 vibe from my dad.
Okay, I hope this isn't too much info, but my dad has owned this car since new, and for the past few years he has been using it for a daily paper route, obviously a lot of stop and start driving. he has been getting the P0741 code on and off for awhile now. I've had the car for about a month now and I have gotten the CEL twice, it stays on for a day or two and then its off for a week or two. I had the code checked at an auto parts store. I changed the tranny fluid and filter, then a week later drained the fluid again and refilled using Valvoline import multi vehicle full synthetic. The fluid I drained out was black, in part I'm sure from the stop and start driving he was doing.
So, when my dad had the car he said it would rev up a little when taking off before the transmission would engage ( this only happened infrequently) , I haven't noticed any problems with it since I have had it. In researching the P0741 code, some people say the torque converter itself could be bad, not just the solenoid. I'm wondering if this is something I should even be concerned about, since the transmission seems fine. One question I have is, should I be able to feel lockup when the torque converter locks up, the engine rus at 2400 RPM's at 60 MPH, anyone know if this is where it should be. I guess what I'm getting at, is, if the converter is locking up or not.
I hope this wasn't too long winded or confusing, but if anyone would have any advice or comments, I would appreciate some responses, thank you, and awesome forum!!