hey jeff, you arent being a pain in the but. these trucks genuinely just love being worked on..
the 1992 volt meter is not a reliable way to measure voltage, open up bs3 and you can see (and record) the exact real voltage before you go digging into/blaming anything on that. if the voltage is going wild then that would all be in the new alternator OR that the wiring to the alternator is not correct or secured correctly since removed from the old unit.
if the intake has been off (while changing intake gaskets) i would look to making sure again that the distributor is set correctlly, also look for any ground wires that may have been moved or are not on clean bare metal (no paint or powdercoat between)
the fuel pressure should be set to 43 plus or minus a pound or so, more than 5# either direction could really throw off the fuel tune. you can check this by watching the fuel pressure while you key on and hear the pump prime (not start the engine, just turn key forward) it will settle once the pump is running so only read it while the pump is running, engine off. this way or remove the vacuum reference from the regulator and start the truck (but it will run rich while vacuum unhooked)
intermittent issues are a real bitch.