Car maintance / problem?

What is your question?

I bought my 2001 Oldsmobile Alero GL1 May 2010 with 108, 329 miles. It has the 4 cyl but it gets very bad gas mileage only 19-20 miles per gallon. The dealership ripped me off charging me $6,000 for the car and they could not tell me if the car had work done to it in the past besides the car fax showing oil changes every 3,000k miles. Car was taken back to dealership less than 24 hours after purchase due to problems and after a week they covered the $1,600 of work conduct at no charge to me. However I will never go back to this dealership due to bad business practices and being insulted by management. The car also idles around 800-1,000 rpm and shakes when put in drive. I noticed brown liquid coming out of the tail pipe when reving it up on the drive way. It struggles at 3,000 RPM also. I only have roughly $1,000 saved up for any repairs or maintnance. Any suggestions? Thank you very much!