If it's a valve, you'd have to pull the head. Since the heads on these are like baby inline 4 heads, it's pretty straightforward to remove a head. However, before doing that, connect a vacuum gauge to the engine and see what's it's doing or if points at a valve. Can try reading this: https://www.motor.co...a-vacuum-gauge/ or google "engine vacuum testing". Lots of sites have tips on how to read. Gauges cost $15 roughly. You can T into a proper vacuum source, and rest the gauge on the windshield (slip under hood gap with hood up) and watch from in the car.
FWIW, I bought a 99' Continental with running issues (it barely ran) @84k miles. Guy I got it from was in over his head with it and bought it at auction. It had one CEL code (forget what atm) and the guy kept saying something was wrong with cylinder 3. After a quick inspection, I found the wires going to the coils (V8 engine, so entire side i.e. 4 cyl. had a lump of wires going to coils) had been chewed on; the rodent was thorough, as every single wire in the bunch had a 3/4" section where the rubber was completely stripped from EACH wire! I cut each wire and soldered back and had heat shrink on each. Car ran better, but still had a misfire (it wasn't throwing a code though). This time, I removed each coil out of circuit and took my ohm meter and probed the center (output going to spark plug) and then carefully probed a connector pin on the coil. I checked both pins separately while leaving other probe on center output. 7 of the coils had virtually identical readings. The last one was 2 ohms too low. Got a new coil and have a great running car I got for nearly nothing.
Anyhow, the point of that anecdote was there was code, but the underlying issue was the wires had been tampered with (stupid rodent, found it's nest under the intake upper) and many were touching each other, and even after fixing that, it took checking each coil to verify a secondary fault was there as well. I'd check each coil. If they all check out with identical readings (mind you, my good coils read 4.5 ohms, and the bad one read 2.4 ohms, so that's enough of a difference) , try swapping coils around, reset the code, and see if it appears on a different cylinder i.e. P0302 (cylinder 2), etc.
Trace the wiring to that coil back as far as you can (if it's wrapped or under plastic sleeves, probably OK, anywhere the actual wires might be exposed i.e. you see the color of the wire, is where you wanna see if there's copper showing. Also look closely for burns or melted sections.