Cold weather misfire and CEL

I have searched the forums and found a couple starting points but nothing that made me feel warm and fuzzy that I knew how to be sure what my issue must be. My '95 XJ has recently developed an intermittent issue with a generally short-lived rough idle, occasional slight misfire (slight enough I'm often not sure if I just hit a bump in the road), generally (but not always) accompanied by a CEL code 27.

Earlier this year I was chasing what ended up being a bad CPS that led me to replace injectors, fuel pump, TPS, CPS, IAC, O2, cap, rotor, plugs, wires, coil. So I am at a loss for what the issue could be now unless there is a short in the wiring harness or a bad ECU. It seems to have started when the first snap of cold weather came in.

Hoping someone here may have some insight on what else I could check, or be able to shed some light on how I can easily test the harness/ecu/injectors/etc. Still getting the hang of diagnosis on EFI.

check the connections on the cps. the one in the distributor. also check crank sensor make sure the wires are not melted on the exhaust.

Well the CEL seems to have gone away after I cleaned and dielectric greased the ECU and Injector connectors. I also replaced the engine temp sensor when I changed the thermostat over the weekend. The engine seemed to be idling and running smoother than it has since I bought it.

However, it was cold this morning (about 15 Fahrenheit) and I noticed it had a miss while running. It doesn't seem to happen at idle but the rig will 'buck' slightly when coasting or accelerating (seems to be more often when coasting but I have a short drive to work so hard to say for sure). Did not really have the chance to warm up the engine on my drive to work so I am not sure if it goes away once warmed up but will check that out later today.

This weekend I am going to pull the plugs to make sure nothing is amiss there, and do a compression check for S&G while I'm at it. Has anyone encountered this before? I am at a loss for what else I could check, everything is new...

Another development which may or may not be related, I just got a CEL code 41 which is 'Alternator field control circuit open or shorted.' So that sounds like a bad alternator, would that cause poor running?

it could as the voltage changes from the alternator kicking in and out

Worth a shot, guess it's time to freeze my a** off for a warranty exchange.

one other think you could check is make sure the o2 heater circuit has power.

Looks like it may be a loose connection somewhere, I drove it over to the next town to have the alternator tested and halfway there my ammeter suddenly started reading what it should be and the alternator tested good when I got there. Haven't had the since that.

I had planned to replace my battery cables with some 1/0 wire this weekend anyway so will be cleaning/checking all of my connections too.

Not sure if it's the same style alternator in the renix era jeeps but I have trouble with the small wires that go to the alternator. I have a dirty connection