stalls in rain

If the camshaft position sensor (CMP) signal is intermittent, then the engine would likely stall when the signal goes out. The signal could be intermittent because of a faulty CMP, faulty wiring or connections. The CMP is located in the distributor. since it's supposedly good in a replacement distributor, I'd be suspicious that the connector is loose or corroded and gives you trouble in the rain, and sets a code. It's possible that the newer CMP is faulty, of course, but you could check it with a graphing meter when the engine has stalled if it becomes necessary.