Cadillac Repair: 1970 Cadillac Deville Rough Idle, fuel line filter, cadillac sedan deville

Question
I recently ran my 1970 Cadillac Sedan deVille with 49,000 miles out of gas by not paying attention.  After that it has had a very rough idle. Yesterday I tried spraying carb cleaner in the carb, and put 2 bottles of a carb cleaner fuel additive in the tank, and drove around a bit.  It is still rough.  It has no problems with power, at normal speeds, just very rough when sitting still, like at a stop light.  Someone at work seems to think there is a gas tank filter in addition to the fuel line filter that might be the problem.  Do you have any suggestions?  I am beside myself, thinking I possibly ran 39 years of sludge through this vehicle.

Answer
There is a micron filter located at the bottom of the pickup tube in the gas tank but I seriously DOUBT that this IS your problem, Because if this filter was plugged up even partially you would have no high speed performance.

Did you change the filter at the carburator ?.