Chevrolet: 96 Beretta - Possible Fuel Problem?, coolant system, vacuum leak

Question
My 96' beretta, which has around 168k on it and has always run very well (dispite this prob) - it has started to sputter when it first starts up and it begins to sputter or chug when sitting at long light or stuck in heavy traffic that is moving slowly.  It doesn't hesitate to start at all, unless the tank is below 1/4, which i hardly ever let it get that low, then with a few pumps of gas it is fine.  This problem has only come about in the past few months and has gotten progressively worse, I have changed the fuel filter, replaced my plugs, oil change, recently replaced the AC compressor and have flushed my coolant system.  And I have no idea what is causing this, it seemed to get better at first when the fuel filter was replaced, but has returned again.  I want to know if it is possibly the EGR or maybe the o2 sensor or both?  or if it sounds more like a vacuum leak.  I had the check engine light come on recently, then when i filled up my gas tank all the way it went off?  but i didn't know if they could read the error after it went off or not?  I am a girl and I am confused, I don't wanna get taken advantage of if I take it in for service.

Thanks so much for your help!

Answer
Hi Ryanne, well you seem to know enough not to get taken advantage of. Ask some of your friends to recommend a good mechanic that you can trust. Have it hooked up to a analizer, it will save you money in the long run. You are probably right, it will likly show the egr or the oxygen sensor. I hope this helps you if you need more info just let me know. Regards, Keith.