engine runs erratically

Check engine light on?
Rough idle suggests misfires and shutting down suggests loss of power. When were the plugs changed last?
The 3.7 needs a plug change every 35,000 miles or so. Use the OEM style copper plugs not the fancy iridium or platinum plugs, those will cause misfires on their own.
Check for vacuum leaks and clean the throttle body.