Ignition Control Module problem

After the winter I got my car out to get it cleaned up to enjoy the summer cruises and I have had a hell of of a time getting it to run like it did. It has a 360 in it and around 2000rpm it would start to cut out and wouldnt rev any higher. I have tested my ignition module because I tested it and it tested bad. I got a new one from Auto Zone and it does the same thing! I put the old one on and it runs fine. When dealing with this thinking it was my distributor I changed it and put on a new cap, rotor, spark plugs, wires, retimed it. Im just afraid to run the old ignition module seeing how it tested bad, but it makes the car run like it did, I just dont want to get stranded because I have overlooked something simple.
I need help to find out why my car could be doing this???
Please help!!!!
Im really leaning towards going HEI! To eliminate all the old ignition parts
when they are tested they run a hight and low tpm test on them if it doesnt go past a certain rpm its a junk modual