i got a 1994 buick century and when i would try to start it, it would either shut off after a few seconds of being on. or i would start it and it would turn on and i would throw it in gear and try to drive off but it felt like it lacked power or just hesitated to move.in the mornings it starts at the second try, after that is when it wants to act up. but some time it doesn't cause me no problems....i changed my muffler, and a few days later maybe a week it started doing that....i don't know if this could be part of the problem or what.......i also changed the fuel filter so thats new......any suggestions...or does any one know what it could be?