03 str within past months was getting codes for bank 1 misfire, cylinder 1,3,7 misfire these plugs have only 15 k on them... yesterday i got p0301 and p1313 do you think i should try replacing the coils and plugs one at a time? [like now do cylinder 1} and if codes return do the rest on that side? or just do 1,3,5,7 all at same time??? and $ is an issue at this time.. do i need to remove upper intake or anything else to do drivers side. or passenger side?? is coils an easy job

 

Replacing the coils is not too difficult, they are about $40 from the dealer. Just carefully remove the plastic cover and you will see the coils.
I think there is a good write up here and perhaps a video on youtube too. I had a persistant misfire on #8 way in the back on the drivers side and the hardest to get to. The coil was covered in oil, I have since replaced the valve cover gaskets, plugs and the spark plug O rings, the engine runs much better now and it doesn't smell like burning oil everytime I start it from the oil dripping on the exhaust manifold from the leaky gasket. You may get lucky and just have to clean the oil off of the coil to make the misfire go away. I put some dielectric grease inside the hole at the bottom of the coil for better contact with the plug.

 

Move the coils around too. Sometimes oil gets in them and can produce that problem.

 

moved them around, all were clean and dry... see other post im gona replace anyway, thanks

 

If it has the right plugs it shouldn't be them. Coils are far more likely, but how many miles?
Any work done on it in the engine bay recently?

 

You can use the more affordable but identical Lincoln LS coils.