Odd Problem

Well, I have pretty much ruled out engine issues or electrical. IT seems more and more like something is slightly awry with my 3000-4000 mile converter. It pulls fine in first, although launch is softer than normal, but when it shifts to second under light to moderate acceleration, it lacks some punch, but the motor is running well. I have to depress the throttle 3/4 of the way down for it to downshift. After that, it will move easier. If accelerating from low engine speeds in third, a downshift is needed to really get moving. At speed in third, acceleration is ok.

I have a feeling that the converter is partially locking. Is this possible? It seems possible that is will only idle at 550-600 rpm in drive, but will idle at 950 rpm or slightly more in neutral/park.