Torque Converter Problems?

I have been dealing with some issues for a while with my 66 Dart 273 automatic. I have rebuilt the carb, new fuel pump/filters, Found TDC and adjusted the timming. All of this seems to make the engine run better which is great but I am still having the following issues...

PROBLEMS:

• Car starts great and idles great in park or neutral
• Drives fine for the first 5-10 minutes
• After 10 minutes when I come to a stop the idle is real low and often the car will stall. I can avoid this by putting it into neutral. When in neutral the RPM goes back up and everything seems fine.
• Last week after driving on the highway for about 20 minutes when I would come to a stop and put the car in neutral it still died on me unless pressed down the accelerator.
• I have some engine shaking/shuddering at just above idle. But this is if in P,N or D. I can get past the shaking if I accelerate fast.
• Loss of top end power
• Poor mileage

I have been reading about it but there seems to be some conflicting information out there.

Any ideas?