Engine Performance problem
1999 Buick Century 6 cyl All Wheel Drive Automatic 165000 miles
1999 buick century ck eng. Light came on-auto zone said it showed running lean, egr, and o2 sensor problems. Advised me to run inj. Cleaner and drive about 50 miles to take care of it. Did that-next day it ran like a wagon sometimes-no power on hills and has a slight burn rubber smell when I shut it off. Took to a repair shop-they say it is a misfire on 4 & 5, EGR, and o2 sensor. Could it be all these issues or is it possiblly the cat converter? Can't afford to take it to umpteen shops. Also, the CEL started flashing -was told I could drive it but it would be rough. Any ideas where I should really take it? I know its high mileage but can't replace it since I am currently laid off. Thanks for any suggestions.