code po301 and random hesitation

I am getting code po301 which is clynder one missfire. new plugs wires cap rotor, tps, and injector. it has a random slight hesitation under light acceleration but does not happen often. I only notice a slight miss when at idle. what should I check next. thanks

Always post the year/engine in the thread. Responses can vary somewhat due to the year and equipment of the XJ.

You have eliminated the usual suspects for a single cylinder misfire. Plug, wire, cap, rotor, injector.

Next thing is to get a compression gauge and test compression of all cylinders, paying of course special attention to cylinder #1.

Can't rule out something internal here. How many miles on this engine?

Do a compression test. This will tell you if it's a mechanical or ignition/fuel source problem. Do a dry, wet, and dynamic/running test if possible. Compare all of the cylinders and see if anything looks suspicious. Could be a number of things... stuck valve, burned valve, bad rings (unlikely, they usually wear together), faulty or stuck fuel injector or bad wiring, carbon buildup (unlikely), bad ignition component. There are a ton of things that can cause a misfire.