Has anyone had a temp sensor or thermostat go bad? If so, what were your symptoms? In a previous post, I was looking for the reasons why I might be having misfires on multiple cylinders, especially when the engine is completely cold. Once fully warmed up, the issues mostly go away. I am leaning towards maybe a temp sensor, although the temp gauge seems to function normal, heat seems to function normal (although been warm this week) and the truck has never overheated.
Would love to hear if you had any type of sensor like that go bad and if so what it caused the truck to do. I'm willing to try a few more small things before I turn it over to a shop.
Quick details: 06 V8, 120K, always premium and syn oil, new plugs, t-body cleaned, fuel cleaners run through, vacuum hoses look ok, pcv newer and coil packs look ok.

 

Just ran and cleared the codes. She is running strong now but she is fully warmed up. Here are the codes if anyone can make anything out of them. I will put in the other post too for later searches:
P0301 - Cyl 1 Misfire
P0302 - Cyl 2 Misfire
P0304 - Cyl 4 Misfire
P0305 - Cyl 5 Misfire
P0308 - Cyl 6 Misfire
P0300 - Random / Multiple Misfire
P0316 - Misfire detected 1st 1000 Revs
I think that is one additional than I had before I cleared them last time, but the seafoam induction cleaning likely triggered some. Now to figure out the pattern...

 

I would be curious to see your fuel trims. When a vehicle is cold, it is in "open loop" until the 02 sensors warm up, in which it then goes into fuel control, otherwise known as "closed loop". In open loop, the vehicle runs off of pre-programmed fuel values and the vehicle isn't able to compensate for recent changes in engine operation (vacuum leak, flakey MAF, etc...). Once in closed loop, the computer can now make adjustments, which would be shown in Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Not saying this is the issue, but would be one of the first things I look at.
Also, any history of EVAP or Purge codes? I see Purge Solenoids stick open and cause misfires too.

 

Thanks for the reply. On my old Discos I always had an ultra gauge hooked in, and you could see when the loop was open or closed. No idea on this one though. I have never had any codes at all for EVAP or purge. Only times I have had codes or CEL was with this issue, and previously when the PCV went.
I started it cold just before and had the small misfires again. No CEL though. I drove it easy for the first mile, but did notice the temp gauge climbed to 1/4 very quickly. I put the heat at full blast and it wasn't up to temp yet. I drove like 3 miles, and then let it idle for 10 minutes while I was picking up my kid. I drove it 20 miles after that and on the highway and zero misfires and was running 100%.