I have a 'salty' aftertaste in a couple if beers I've fucked up.
Put down to two things through my own research and feedback from someone I trust and respect (the two aren't necessarily in conjunction with one another, nor are they mutually exclusive):
1. Excess sulphates in water profile (in my instance, unsure if excess of other additions can give a 'salty aftertaste')
2. Underpitched/yeast-health issues.
%99 of the members of this forum know more than I do, but I would look at those two issues for a start (depending on grist, water, and yeast).
Astringency has been mentioned, in which case investigate sparging techniques, mash pH, and gravity of final runnings. I was advised to do this last September and it has helped enormously. A high brewhouse efficiency ain't always what it's cracked up to be...
I hope you solve your problem; if I was to resort to cliche I'd quip that the chief daemon is in the minutiae.