Will a motor out of a 99 Ford Ranger 4.0 motor and trans fit in a 2001 Ford Ranger that had a 3.0 in it

 

Welcome to the forum

It will "fit" since Rangers came with the 4.0l in 2001, 5.0l V8 will also "fit"

You need to swap engine, transmission, engine wiring and computer over, change motor mounts, radiator, and the exhaust system
And some interfacing of the wiring as the power harness will be slightly different between 1999 and 2001, and its specific to those years, so unless you can find someone who has done the exact same years on this swap there won't be any direct info on it, you need to test and splice

Cost of a swap like this, even if you get engine/trans/wiring and computer for FREE, will still probably be more than fixing the 3.0l Ranger and selling it, then buying a 4.0l Ranger, just FYI
V8 swap is EXACTLY the same work as this and you have a V8 Ranger in the end, so you should consider this, and there is ALOT more info on the V8 swap