Torque Converter?

All symptoms are from an automatic 1994 z28. Recently i have had the low trac light come while driving. A couple of days ago the light flashed for a couple of minutes after first starting and driving then it quite for a few minutes until i started to accelerate again. The light seems to come when the transmission is to downshift from overdrive to drive, in like a passing situation. May not be of any help but when i rev the motor in park it seems like something is moving n the viscinity of the flywheel/torque converter. The transmission is freshly rebuilt with less than 1k miles on it with a rebuilt torque converter also. My question is, could the converter be bad? Is there any way to inspect it or eliminate it as my problem?