Sounds very much like what my car was doing :-(
Lower intake manifold gasket was my issue. leading to damaged lifters & burnt valves due to overheated engine...

Does the temp guage fluctuate? warm the car up to operating temp and see if the guage goes up & down continuously
Has the low coolant light come on at all?
smell the exhaust, does it smell sweet at all?

my car idled rough, stuttered up until about 15Mph