Doesn't sound like it starts and idles "mint" to me or it wouldn't be doing what it does.
AND if that truly is the case then you have a bad converter.
If you don't have a bad converter, then the engine doesn't run and idle "mint".
Get where this is going? :D
I have seen people driving cars with two cylinders missing because of out of order plug wires that say it runs great.
Can you video this problem in neutral at idle, then putting into gear at idle, then in gear with just enough throttle to keep it running?
My neighbor came in with a new/different car one day and asked me "well, what do you think?" "It sounds good doesn't it?"
My reply was "Sounds ok if it was a V6, but it's a V8 missing on at least two cylinders". (plug wires were wrong and when I put them in right it cleared right up)
Guess what he said? :D
"It doesn't sound as good as did"