Cat pees everywhere

So, about 16 years ago one of our favorite cats died when I was a kid. He died from an allergic reaction right in my arms. So we decided to get another cat that looked the same and as fate would have it,  had the same birthday. He's a cowardly thing and will be 16 in June, but for the last few years he's being peeing anywhere but the litterbox. In hallways, behind tvs, on tv stands, in the corner, on rugs, everywhere BUT where he''s supposed to. When it comes to pooping, he'll right next to the litterbox. For an older cat he seems to get around fine, climbing the stairs no problem and he likes to be loved on, though you have to go to him. About a year and a half ago my mother gave him away to someone else (To my distress, I was living in another state at the time), but the person brought him back because he stayed under the couch the whole time, peeing there and didn't eat. By the time I cam back he was a shriveled version of his old self and since he has recovered. Vinegar doesn't work, either he'll ignore it, or find someplace else...and I can't really expect to douse the whole house in the stuff. My mother had fed up with him and is torn with wanting to get rid of him and to keep him...though practicality is starting to get to her. What can we do?

I wasn't sure from your post but this cat lives with your mother, right? I'm assuming it doesn't live with you?

Have he seen a vet to rule out a UTI or other health issue? That's a good place to start.

Also, what kind of litter box do you use? If it's lidded or has high walls it may be hard for him, or less appealing, for him to climb in and out of. You might try a more shallow, open box for him to do his business?

I had a similar issue when I took in my mother's elderly cat. When she first came into my home she hid under the couch or behind the recliner and would only poop and pee there, she was too afraid to come out and use the litter box. I ended up isolating her from the rest of my house and cats by setting her up in my room and leaving the door closed. Eventually she became comfortable, felt safe and started using the box.

first get him to a vet as it could be medical. any time a cat suddenly showing aggression  or litter box problems, it their way to tell you there something wrong, please take me to a vet

He lives in the family home where I am currently living. He has been to the vet several times and there's nothing physically wrong with him. The litter boxes have small walls. Running out of ideas here.

Is he declawed? I know this kind of behavior can be common in cats who have been declawed.

Have you tried changing the type of litter? If it were my cat and health issues were ruled out I might isolate him for a time and try out a different litter to see if he prefers it.

i agree keep him in a room and try different litters until you find one. use an enzyme cleaner to clean the areas he went

He is not declawed. We have tried separating him from the rest of the house before but he would continue to "go" elsewhere. We haven't tried different other litters because they don't sell many around here and she's afraid of "clump up" cat litter getting into the cats lungs and killing them. I have forgotten to mention that we have other cats, but he seems to get along fine with them

with cats you generally don't have to worry about clumping litter. the kittens you do because they will eat which is why if you got a kitten it recommend to get non clumping litter

Sounds like you should definitely try isolation from the other cats, finding a litter that works for him and go from there. Seems like the next step. If that doesn't work (and I would bet money that it does) you can move on from there. Sounds like he needs his own space. Are there any cat type furnitures he can climb on? He may feel more comfortable in a higher up hiding/resting place where he can survey his surroundings.

Try different kinds of litter boxes (big ones, round ones, hooded ones, etc) and try cat attract. Place the boxes in different locations all over the house and see if he uses one.  Good luck.  I hope you guys are able to keep kitty especially in his old age.