I've got some Issues... well not me, but my car!

I think you have multiple problems;
A noisy pinion bearing, and maybe a loose pinion yoke
a bent driveshaft,
possibly out of balance wheels,
and you engine idles like it is getting too much EGR,lol.
IDK about the slapping,
unless you don't have a SureGrip, then it could be that there is something wrong inside with the spiders and crosspin.