Agreed. After putting that much work into your car, I think you should try to get your money’s worth from it, and then consider getting rid of it before you commit to spend more on repairs.
Regarding your next car, I recommend you look into programs where people donate their old cars, where they get fixed up and sold or donated to those in need. NPR has a vehicle donation program, but I don’t know where the cars end up. I once donated a car to the Miami Rescue Mission, but that probably isn’t helpful unless you live in South Florida. The point is, call around to the Salvation Army, the United Way, and maybe some local churches to see if they have such a program.