2001 - 65,000 miles. Have owned it for around 2 months.
It's rare - has happened maybe ten times total - only cold starts. Right after engine fires, last a second, then quiet/normal.
Almost sounds like a loose heat shield or something. Any chance it could be the converter?
Thanks for the help ----

 

Could be your starter not disengaging when you release the starter button. Occasionally happens to me cold in the winter but never warm. The fix involves removing and cleaning the starter. You can find the DIY on this site. I have yet to do that as it has not happened for a long time.