code PO301. what does this mean? on 2000 Ford Taurus

after code po301 came on I was told to get a diagnostic test to see the exact problem. Where do i have that done? how much should it cost?

This means that cylinder number 1 has a misfire. I would begin with a new set of plugs and wires, if they have over 60 k on them.
1 more answer
this is an obd2 trouble code table, it can help you understand the meaning of code.

and for p0301
you can try this

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
and this tool can do you car.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.