2003 Dodge Neon rough running help!

Hey guys/gals, my son Garretts girlfriend Ashley just bought a 2003 Dodge Neon. It was bought certified about a month ago, but she is having some issues with it.
1. Intermittent hard start
2. Engine shakes when started
3.When coming to a stop the transmission doesnt seem to down shift properly(hard shift??)


The following "repairs" were done to it today and I as of yet have to verify it....
Scan test $45
Replaced cam sensor and spark plugs, once repairs were done today it seemed fine at first, but after about an hour of driving, some of the issues are still there...Im not familiar with this new of a vehicle, what about Idle Air Control?? Any input is appreciated, I think she got a good deal on the car $2500 certified and its a cute little car with 173 kms

Thanks
4spdragtop