Persistant miss fire

I have a 97 xj 4.0 150,000 miles. I have a persistent cyl 1 miss fire thats odd. I have replaced all ignition componets from the coil up expt the dizzy. What happens is every2-3 weeks I will get a cel and runs rough at idle fine when driving and will get persitently worse until it doesn't fire driving. and as soon as I change the plug it runs great and cel goes off shortly later. The plug that comes out looks fine and I run auto lite coppers gapped correctly. I have also tried an anti fouler and a new inj to no avail. I've been batteling this forever and I'm starting to think I need to yank the head and have it freshened up. Any tips guys please?

You have addressed many of the "usual" suspects. Plug, wire, distributor cap, injector.

Next up is a compression test. Good data = good decisions.

Run the compression test on all cylinders and see if cylinder #1 is in spec with the others. The target compression for the 4.0 is 120-150, with no more than a 30 psi variation between cylinders. Run a dry test, THEN a wet compression test.

Post up what you find!