1998 Chrysler Cirrus crank sensor

Have your computer scanned for codes. Many auto parts stores will do this for free.
Post the codes here (if you have any) for further assistance, BEFORE you purchase any parts.

Meanwhile, check all vacuum hoses for vacuum leaks. Correct all that are found.

You could also try cleaning the throttle body:

Use carb/throttle cleaner and a rag or small soft bristle brush (old tooth brush works well) to clean the throttle body. The engine should be off during this process.
1. Remove the air snorkle that runs fromthe air filter housing to the engine (throttle body).
2. Have an assistant to hold the throttle open by depressing the gas pedal to the floor and holding it,
3. Spray the cleaner into the throttle body. Use the rag and brush to scrub away the gum build-up. This may take several cleanings before it is complete. Close the throttle.

4. When starting the engine after a cleaning, it will be harder to start than usual. Hold the throttle open and rev the engine once it starts. Don't over-rev the engine.