I would check all the ground wires on the manifold, and the braided ground wire from the firewall to the valve cover.
another thing you might want to know is that just because the in tank pump is running dosen't mean it is working.
I have noticed that the hoses inside the tank on the in tank pump sometimes get old and crack.
I'll think of some other things for you to try if that dosent work.
one more thing, if you haven't found out if figured out if it is in the ignition, or fuel system a quick way to find out is watch the tachometer; when it stalls, if the tach drops instantly, it is in the ignition, if it drops slowly- fuel system
I hope this helps

-Sam