What could be the reason I get no spark to my coils? There is no spark in any of the three coils.

I am having starting problems with my 1995 Riviera.  It started with stalling out while driving it, then it was stalling
out and wouldn't start back up for a while.  I had to wait a while, then try it again. I changed the fuel filter and the
spark plugs. It started but would die almost immediately.  Now, it won't start at all. It turns over, but won't start. I
have checked the connection to the crank sensor, all of the fuses, and am stumped.