I can start it one time and it runs smooth. I turn it off and start it again and it runs rough as all-get-out. Start it again maybe rough or it maybe smooth. Just had the timing belt replaced about a month ago and commuted about 500 miles before this started to happen.

 

You have a few options here to check..
1. check the battery
2. spark plugs
3. oil level
4. fuel cap ( the car gas tank has to be under air pressure)
5. is your check engine light on
6. intake manifold gasket leak

Just a few things to look at.. And who did your timing belt replacement.. Timing belt is the main heart for this car..