Why does a pot hole make it feel like bottoms out ?

Do you mean OEM shocks? If so then that is why it feels like it does, you need much better shocks, at least two way type.

Several possible reasons, here are a few................... OVERinflation of tires. Many people use the MAX pressure a tire is marked with, instead of what the vehicle recommendation is, which results in a stiffer tire that is more reactive to bumps. If a tire is rated at 44psi, and is run at 44psi, instead of say 32psi there is a huge difference in ride. If this is the reason, don't feel too stupid, many employees that work at tire mounting places ALWAYS inflate to what is marked on the sidewall, regardless of what it says on the car sticker. ....................... LARGER DIAMETER than stock wheels-a shorter sidewall means there is less distance between the rim edge and the road surface, so a tire NEEDS to have a stiffer sidewall than the OEM size/profile tire does , so that it does not risk rim contact with the road when it hits a sharp bump, such as a pothole, which results in a stiffer ride. Generally, it will be necessary to reduce tire pressure when going to a larger diameter or wider tire-and the greater the size change, the greater the adjustment will be needed............................ Larger diameter/same width or wider TIRES than stock-both having a higher load capacity at the same pressure as stock tires, will distort the contact patch (lifting the edges of the tread) will result in a bouncier response to the same sharp bump..................................... HIGHER PLY RATING-or more plies in tires than the original will ride stiffer at the same tire pressure. Running TRUCK tires instead of passenger tires on your Ranger, and inflating them to the sidewall MAX pressure (which can be as high as 80psi) can make a tire rock hard and feel as if you have no shock absorbers.