2005 Ford Freestar emission light on desh bord.

The blinking of the light indicates that what is happening could damage the catalytic converter, and it probably a miss-fire. Do not drive it any more than you have to. Try to get the code or codes read and post them here for us.

The flashing light indicates the most serious of conditions and you're supposed to stop the engine as soon as possible. Don't keep on driving. Too much raw fuel is going into the exhaust system and is going to overheat and damage the catalytic converter.

The engine vibration is due to a misfire. That will send unburned fuel and air into the exhaust system and will cause that overheating of the catalyst. The Engine Computer detected that misfire condition and set a diagnostic fault code that will indicate which cylinder was responsible. It is important now to not disconnect the battery or let it run dead. Doing so will erase that code, then that valuable information will be lost. Many auto parts stores will read the codes for you for free. It's important to understand those codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. With the exact code number we can figure out where to start.