1998 Ford Escort Car is acting very odd!

My Car has been running perfectly fine the 4 months I have had it, the only problem I had was the idle air control valvae has been messed up and it had been causing my car to ruff idle and sometimes die. The problem i'm righting about is yesterday my car died on me twice in a row and it was od casue the third time I tried to crank it it acted as if the battery was not connected properly. So I got out and took the posotive side off the battery cleaned the post and the cable end. I went to stick it back on and it kept acting like it had power on in the car and it started smoking when I tried to crank it( wire smoke). When it finally cranked it sounded as if a rod is nocking, but it also sounds as if it is bogging down as well. Anyway as you can tell I am very confused about it.