The SOHC 4.0 is an engine I am wary of, but which can also be very good. Good ones seem to last a long time, but if you do get one with timing chain problems, it's not cheap to fix. They were supposed to have improved parts by 06, but I have heard of 06-07 trucks still having the issue. Interestingly, for a long time it was Ford's only gas engine in the US that still called for 5W30 instead of 5W20.
If it is quiet on a cold start, I'd probably buy it. Whenever the time comes to replace my 02 3.0 with 240k miles, it's probably going to be a SOHC 4.0 since the 3.0 went out of production in 08 and I prefer Super Cab automatic transmission trucks. You can get 2.3s in that configuration, but they aren't very common and I'm used to having a V6.
One of the most common issues on the SOHC aside from early timing chain issues is the thermostat housing. They all need it at some point. Not that big of a deal, but one of the first things you look at on a SOHC 4.0.
Anywhere that has regularly salted roads in winter, you need to check for rust. The rear of the frame can get eaten up bad, even with little to no rust showing on the body. This is true of all vehicles from that kind of climate though. I've seen 10 year old F-150s and Silverados with crossmembers about to break off and holes in the frame.
The IFS front end can be a ball joint eater. Replacement control arms and lower ball joints are easy to find though. Shop around if you aren't doing the work yourself. I've found prices vary widely. Some guys can knock out a Ranger front end in their sleep before lunch for $300-500 labor, others want $1k+.
Overall, this era of Ranger is pretty solid. My 02 has been an absolutely great truck and will probably be replaced with something similar if possible. You do need to look the truck over though. I jumped on my 94 Ranger six years ago because of the rare options it has, but it was run hard and put up wet by five previous owners, and it has been much more problematic than my other trucks mostly due to too much mud and not enough cleaning and maintenance. Less of a concern with 2wds, but avoid trucks that have literally been run into the ground.