89 XJ starting to miss fire?

89 XJ 6Cyl 5sp. just started a slight miss @ about 2K RPM. Short event with small kinda single bark at the exhaust. (Not really a backfire.) Not constant, sporadic so thinking CPS getting dirty from oil leaks? Anyone pulled and cleaned CPS with any luck?
Being intermittent it will be tricky to find so any ideas on other things to check? I did the all RENIX connectors service less than a year ago and it has been running like a champ until this week.
Engine has had heavy service over the last 4 years so many new sensors, through cleaning of grounds, new vacuum lines, ignition switch and fresh 4 hole injectors. :dunno:

Cleaning the CPS of metal fines from the clutch may fix such a problem on Manual transmission rigs. Worth a try.

Check the cat with a light tap from a rubber hammer to see if the internals rattle, meaning they came loose and are wandering around and blocking the exhaust enough at 2000 rpm to cause the issue.

Check the fuel pressure again at 2000 rpm (fuel pump capacity/flow test) and the FPR vacuum line for the smell of fuel.

Mine was bucking at a round 2000 RPM (2000-2400 RPM) it would also crap out at higher RPM's above 3500 or so. It was worse with a steady throttle (cruising) and lightly accelerating (high vacuum conditions). If I full throttled I could push the RPM's right through the trouble area with no issues. It also rarely caused any problems until the motor was up to operating temperature.
Turned out to be my O2 sensor.
I internally thought it was a torque converter lock up problem , then a fuel issue, it was neither. It started out small and got progressively worse over a period of months.

In fact it has happened a few times for various reasons, once was the O2 sensor and once my O2 sensor harness melting on the exhaust manifold behind the power steering pump bracket.

On my 87 it was flat spot in my TPS. I did an OHM test on the TPS as I worked the throttle and their was a dead spot in it. That flat spot in my TPS was right were I usually kept the throttle for long trips on the interstate (my sweet spot).

Thanks for the info guys! All things I will check.