2.4L Cold Start trouble

Well, I cant figure this out, and hoping someone can give me an idea of where to go from here.
So I have a 2002 2.4L with 200K on the odometer. After many years of problem free driving, a short time ago on the way to work, she start stumbling and missing, CEL flashing. Take it home, check codes. Its a misfire in cyl 3. I swap coil with another and sure enough misfire follows coil. I decide to change all coils (went with NGK) and while I am at it change plugs (Denso). Start her up and alls seems fine. Next morning I start her up and it seems to be idling low. As I head to work and pull away from my drive she stumbles/misses as I shift into 2nd. I decide to keep going and when it reaches temp alls well, no miss no hesitation. Running best since I bought it 6 yrs ago. But every morn, same thing. No CEL. Other symptoms, seems to not fast idle long enough and sometimes low idle. Mileage seems a little worse. But once again once warmed up it runs and idles great. I tried changing the IAC, made no difference.
Thanks for any advice.

 

since it is repeatable lets do a simple test first. When you get home at night pop the hood and let her cool off for 10 minutes or so and with a rag, slowly take the radiator pressure cap off. Start her up and make sure she idles OK then shut her off for the night. In the morning leave the cap on but not sealed and start her and see if she misses. If she does not miss then there is coolant seeping into the cylinder(s). Repeat this test over a couple of nights just to be sure. I think there are a couple of issues and they are heat related or lack of so to speak. If you have a scan tool see if you can see what the PCM shows as ECT, engine coolant temperature, when cold. There are 2 water temp sensors, the single wire one is for the coolant temp gage, you are looking for the 2 wire one on the back of the head, if I remember correctly.

 

Thanks for the reply Glamisman. I will give this a try over the next few nights and report back. The ECT was going to be my next step since its relatively cheap. But it looks like a B***ch! to get it replaced. I so not have a scan tool just a code reader. More info, I haven't seen any smoke out the pipe and when I rechecked the gap on the spark plugs, they look like black and sooty with only a few miles on them.

 

Its been a week or so of driving and the miss/stumble is getting worse every day. Now misses/stumbles on any acceleration cold or warmed up. Runs fine when just cruising. Still no CEL/codes. I will throw a TPS on tonight and see what happens. Seems like always misses in a certain spot on the accel pedal travel.

 

sounds like the ECU had it tuned and you changed its hardware so it needs to retune. I'd disconnect the battery for a few hours to clear it. If its a gaskey leak, look on the underside of your oil cap, see any light colored gunk? If so, you have a head gasket leak. I had to rebuild mine at 180k after my thermostat failed and it heated up too much. cost me $2800 for a new cyl head and valves.

 

Ended up being one the new coils I installed.

 

what were the steps you used to determine it was the new coil(s)?

 

After installing a new TPS and a new ECT made no difference, in fact the miss/stumble got worse everyday. I decided I had reach the limit of my ability to fix it. I called my mechanic and made an appt. Day of appt I go to drive it to him and the truck will barely run. As I am on my way, what pops on CEL! Get to the shop he reads code, missing cyl #2. New coil and his labor $160, other new parts I didn't need $145, but runs like new.

 

damn, tough enough to figure some of this stuff out but when "new" parts are no good...