! HELP 1987 Buick Century HELP!

I have a 87 Buick Century 2.8 with 114,000 miles and I just got a full tune-up on it from my sisters boyfriend. The car has always ran fine, no big problems. Right after he was done, I took it home and I noticed it was acting up. Everytime I stopped at a stop sign, and then went it was like "missing". It acted like it wanst getting enough gas or something. Almost like when you drive a stick, and dont give it enough gas when you let the cluch, it almost dies. My car hasnt died, I dont really think it will either, I just give it more gas and it drives fine. Im no mechanic so I have no clue whats wrong. Thats the only way I know how to explain it. And aslo the "service engnie soon" light has gone on and off about 4 times sinces the tune-up. I checked all of the spark plug wires, and they are all in the right firing order. So maybe its has something to do with the fuel filter he put on? I dont know.

someone please help. Im going to be driving to Kentucky from Oregon in about 3 weeks, and I really would like to get this fixed asap.

thanks

Jaime