I'm not 100% on this but I'm pretty sure a 94 does not have a MAF relay.
Yes, if the MAF was bad it could cause lots of running issues.
If you want to try something without spending a dime, unplug the MAF, with the key off. Car will run in open loop, CEL on, fans on, w/ no 02 sensors controlling fuel trim. Not saying this will fix or prove anything but if it is the MAF you suspect, take it out of the loop. Then drive it and see later if you still have your issue.
If your running so rich you notice with all the soot. I think you should start with having the fuel pressure re-checked. Just because something was ok last fall does not mean it is ok now. I've seen new parts fail out of box for crying out loud.
A systematic approach is the only way to diagnose an issue like this. Check fuel pressure ensure it is ok, then move on to other checks. Like seeing if the ECM is getting proper inputs during all operating conditions. This would involve a scan tool set to read/record live engine data.
