1987 bonneville not runing right

[Porkchop2007]

Hello, I just got it out of the shop about 4 weeks ago, had the oil changed, new tires, and fuel filter. Its been running great awsome fuel mileage. Today I was at the gas station, waiting on my girlfriend and it started chugging, I hit the gas and it ran fine for about 30 seconds and did the same about 4 times, we left it seem to be runing fine, drove about 1 mile and it started chugging again and almost sounded like a lawn mower. I could also smell sumthing burning, I think it was oil. I drove it back to my house "a mile" and it was running fine again. If any one has any ideas it would be helpfull.

Thanks, Ray