So...I refinished my oak hardwood floors. I took off a dark mahogany stain back to natural wood. Went from 36 to 60 to 80 to 120 grit sand paper. Cleaned (what I thought was good enough) and started putting gloss polyurethane down. I put on 3 coats. After, I noticed it was extremely grainy. 10s of 1000s of gritty spots or air bubbles. It's been over a week now and, parts of the floor are peeling, and gooey under where it is peeling. Everything went fantastic during the sanding process. Then I buried myself during the poly process. I used a lambs will applicator pad. I couldent stand looking at it so I'm going to sand it again, and retry. However I started sanding my hallway (because I can't get a drum sander down it.) I'm noticing that it's extremely hard to get the new poly off. Could I cans it down smooth and repoly or does it all have to come off?

How long did you wait between coats of finish? The first coat will dry on top and still be curing when you apply the second coat of finish. After two coats of finish I recommend waiting a few days to get hard before adding the third coat. The final coat will be susceptible to abrasion if the first coats do not have a chance to dry enough. A very thick floor finish will take several days to a week before it becomes tough enough for normal traffic.
I've seen little gritty areas from using a can of finish that has been opened and partially used. The air above the finish will react with the surface of the partially used finish and start to cure, making a skinned over surface which when stirred
in will have what looks like a rough sandy surface when it is spread and has dried.
Sanding fresh poly will make dust that can cause spontaneous combustion if not spread out to dry, so don't keep the dust in a closed container that is not fire proof. Spread the dust out onto newspaper or a plastic sheet so it can dry, or dump it into a 5 gallon can partially filled with water.
It is possible to screen/sand off the top coats of a finish without taking off all the finish. Wait for the finish to cure some before you start sanding. Wrinkles and gritty surfaces will smooth out before all the finish is removed. Once you get the surface smooth again, you can add more finish to get a good looking floor without going to bare wood.