Hesitating in park

Hey Ford Taurus owners.
2000
SES model
107k mikes
v6 not sure the liter, smallest one
oil changed like clock work


A month ago I noticed that my car is hesitating in park.
When it is drive with the brake on I do not notice the hesitation.
I changed the new plugs and wires and it did not go away.
I do not see any hoses loose.

Could this be the fuel filter?
Should I run some fairly expensive fuel cleaner through it?
I am using cheap gas, too expensive to use super unleaded.

Thanks for your help!