1990 ABS and Eng prob

[barobb]

hello there,
I recently bought this 1990 grand prix se for my doughter and I drove it for a few days and the anti-lock light flashes sometimes and sometimes it just stays on, the brake light is sometimes on also, I found a plug off of the master cylinder, plugged it in, still no help, before I plugged it in, everytime you step on the brake pedal you could hear the abs motor run, now the motor runs all the time, since I have encountered this problem the motor has no power at start-up everytime, after it runs for a little bit it will finally go. At idle it is real rough and I have smoke coming from one side of exhaust, the exhaust smells like gas, I don't know where to start. Any info would be greatly appreciated.