After valve adjustment stall issues.

That change could have gone either way louder or quieter. didn't say which way he adjusted them, tighter or looser
I bought a 69 D100 some years ago that had no power. I mean you could get rolling in 1st and 2nd but shift to 3rd and it absolutely would not pull itself. 2 young brothers had bought it out of state, dying to get home as their parents were split and they came back to the area because they couldn't do without the kids they grew up with.
They made it home but sold it out of desperation because they couldn't make it run right.
They'd changed (or maybe had someone else change) the clutch thinking it wasn't grabbing good enough to pull in 3rd, changed from column to floor shift, tuned it up, and still couldn't get any power out of it. I got the truck and 1st thought was that this engine was shot. I did a compression test and 3 cylinders showed NONE.
Come to find out they had adjusted the valves so tight that a couple wouldn't close. I did a valve adjustment and it was a whole different truck.
Another one I should have kept