First of all, how do you know its a stock pitman arm? The dropped arm look the same, just instead of the drag link bolting from top down, they bolt from the bottom up. Visually they have the same amount of angle/drop. Make sure yours isn't a drop arm already.
Winner winner chicken dinner. You called it, sir.
i was told that there was a stock pitman arm on there by one of the mechanics at the dealer i bought the truck from. He put all new ball joints on it and a brand new steering stabilizer before i bought it. I'm pretty sure the PO traded this truck in because of the bump steer and they just threw some new parts on it and called it good.
My mistake, i believed him. I ordered a new drop pitman arm. When it came in i put it side-by-side with the one on there and it's identical. it also is bolted from the bottom up.
Yesterday, my steering brace came in and i went to install it. I couldn't complete the install with the stock hardware it came with because apparently when they did my lift, they had to move the sway bar forward. To do this they put some kind of sway bar relocation bracket on the truck that moves the sway bar down maybe an inch and forward maybe 2 inches. This bracket needs 15mm hex head flange bolts to get inside the bolt cavities. The steering brace came with standard M10x1.5x40mm bolts and there's no way a socket is getting inside that relocation bracket.
But.... that was interesting to see/learn. Also, my pitman arm bolt was on there barely tighter than hand tight.
What i did do last night was tighten up the steering box a little. I sat under the truck yesterday staring at everything for a good hour and trying to take deep breaths and think everything through.
I have to go back to the basics here and start over, check every single component. I started by checking the steering wheel play and i had about 3" left-right, way more than the 1" it's supposed to have. I tightened that down a little and it's a little better, but, i wanna get the flange bolts i need, put in the steering brace, then go from there....
but yeah, good words on your part. you called it.
Secondly and most importantly is that the drag link and tract bar must operate at the same angle from frame to axle. If they are not at the same angle now then that is obviously a lot of your problem right there. If they are are at the same angle then adding a dropped arm will mess you up more. You will need to buy a drop bracket for your tract bar.
I'lll admit i dont know enough about suspension/steering yet to comment on this. i'm more of an engine guy (motocross, pwc, atv's, two stroke, four stroke, etc). I need to learn more about steering, suspension, the components, the geometries, etc.
I'll read that again 100 times until it makes more sense and googling/videos in between.