I drive a 94 (blazer) as well.

Well I mean theres the 3 parts of a running engine ; the two most fixable would be spark and fuel delivery..
The rough running could be a rich or lean condition and now that you feel like the vacuum leak has been ruled out; I'd say to address the spark issue. I had a minor rough running condition and changed my plugs, rotor, cap, and wires.
Just use the basic AC delco plugs. They're cheap and the truck doesn't need anything tooo fancy for just basic driving.

If ignition doesn't fix it I'd start with a fuel filter and maybe some injector cleaner.
From there I'd look at the injector assembly itself if you have the spider. You can check the assembly for leaks quite easily by removing the "vortec" cover and the plenum tuning valve underneath. BE CAREFUL NOT TO DAMAGE IT!
Look for any washed down areas that are cleaner than the other. Passenger side may be a regulator and the driver side may be a nut kit..

Does the rough idle occur under one condition such as a cold run?