Gta 4 is indeed known for it's terrible handling when it comes to cars, there are quite a few handling mods out there. I personally prefer this one:
Not only does it have better handling but it also allows you to go alot faster. If I remember correctly all it takes is dragging and dropping the folders into the right path. Make sure you back-up the files first before replacing them . just in case you don't like the mod.
I'd recommend using a controller aswell if you have one, should make the running somewhat easier. I don't know any mods for that.