low compression

My 1998 XJ is throwing a code of P0301 which i believe is misfire on number 1. I checked compression and it is lower than the rest. Its not smoking or burning oil so i assume its not bad rings. Someone told me could be a worn rocker arm. Is this possible? please help any ideas

What are the compression test readings for all six cylinders ?

Get compression readings for all cylinders. With this test, the devil is in the details.

If you have a low cylinder, add a teaspoon of oil to the cylinder and re-do the test on that cylinder. If the compression comes up with the addition of oil, it is likely piston rings. If the compression doesn't come up, it is likely in the cylinder head.

Compression for the 4.0 should be 120-150 psi, with no more than a 30 psi variation between cylinders.

1-89
2-140
3-138
4-142
5-140
6-136

If it was rings wouldnt it be smoking and burning oil

I read that the 4.0 dont like bosch plugs and i have bosch +4 in it

While it doesn't like the bosch plugs, that is not the problem with your low compression. Is it making any abnormal sounds? Have you pulled the valve cover?

nothing abnormal the code actually comes and goes and i am pulling the valve cover today