Timing Tensioner problems of the 2000 Chevrolet Impala

I have a 2000 Impala with approximately 161,000 miles on it. The car is used and I am the 2nd owner. I went to have my normal oil change as I had noticed the low engine oil pressure light had come on. The car had been running out of oil frequently, but I didn't see any oil leaks. The print out after the oil change stated multiple oil leaks. But there was never any oil on the ground. The car had been running very rough and was staring to run warmer than usual. Not hot, but past the middle line on the temp gauge. And I had noticed a burning smell after driving, but never saw any smoke. This all started in April 2014 and has been ongoing. I've taken the car to a repair shop and nobody seems to know what's going on. Now July 5,2014 I went to turn left and the steering wheel was extremely hard to turn. I had to put a lot of muscle into turning the wheel. I checked the power steering fluid and saw it was low so I topped it off. Problem should have been fixed right? wrong. It got worse. I took it to a different repair shop and was told it was the tensioner pulley. O'er $100 later, the problem has gotten worse. When I turn left the wheel stays stuck and I have to jerk it back straight. Thus is a safety hazard as I transport my family in this vehicle. Since these problems stared the car eats a lot of gas. Going 5 miles should not use almost a quarter tank of gas and the check engine light comes on and stays on at random times, during theses times the car eats a lot if gas. When the light is not on gas mileage is ok. This is very dangerous.