318 Internal Vacuum Leak?
As to a vacuum leak;
You said it passed all the external leak tests AND, that you have pressure in the CC, so
IMO, if you did a good job, then you can rule out a vacuum leak.
By backing out the speed screw, the throttle valves are fully closed. therefor, air is entering the intake from somewhere. The most likely sources are the booster hose or the PCV system.
BUT
If your TB has an Automatic Idle Speed Control, there is a good chance that it is open just way too far. That device has to be synced to the minimum throttle opening to tell the ECU about how much air the engine is getting.
@Cal Tonsley mentioned this, above.
BTW
. As a broke college kid I've Any suggestions?
Since you're in the HOBBY, and already have a Sniper system, at such a young age, You'll not get much if any sympathy from me. lol........ I'm 71, and I've been down that road more than a few times. I run a carb. There is a good reason for that.. Me and carbs are good friends, and once set up, just about nothing ever goes wrong with them, and if you had one, you wouldn't have
"put way to much money into trying to figure this out."......... lol.
Ok, I'm done yanking your chain. I'm sure you'll have it running like a champ real soon.