A little backstory first, most likely unrelated, but just in case. A few months ago wen hurricane Matthew hit nc, my truck started missing really bad, but never threw a code from the water. It dried up the next day and I didn't have anymore issues. 2 weekends ago, my fiancé and I hit a few trails and got a little muddy and wet. Misfire happened again. This time it sheriff a code. I used my edge evolution and gott a misfire on #3 cylinder. My plugs only have 30k on them so I bought 8 motor craft cop and 1 new plug. I replaced all the coils and #3 plug and everything seemed fine. Here's where the transmission concern comes in. Heading into work yesterday, I noticed the truck bogging down after it shifts into 3rd. I also noticed a slight miss at idle when the engine is still cold. All symptoms, motor and trans are symptom free when everything is at operating temp. So two questions, with the misfire, any ideas? I made sure to use dielectric on all contacts when I changed the cop. The transmission has never had a flush or filter change and it have 172k miles on it now, I'll be doing that this weekend. Does anyone have any other ideas of what could be going on? I'm stumped. Tia

 

change the rest of the 7 plugs and service the tranny. I'd do a drain and fill with 4.5-5 qts of decent mercon v, change the trans filter, and redrain and refill 5k later (no need to change the filter again) with a good quality mercon v, such as MC or equivalent. See if that helps.

 

Yikes, if its not been serviced to this point, plenty of people will tell you not to change that fluid now. All the gunk that's holding it together starts to break down, and it goes from bad to worse. There is plenty of debate about this topic here, although not a whole lot of "after" follow ups. I had an accord several years back that had the transmission beginning to slip. Not knowing better, I had the fluid changed/serviced and it got much worse, to the point I couldn't drive it anymore. Search that up.

 

i had a s10 before I bought this truck which I bought in 2011. I changed the transmission filter at the service interval and it went out a month later. The guy I worked with at the shop said with transmissions, if it ain't broke, don't touch it. She that's what I've done with this truck. Hoping the flush I do Sunday will fix it.

 

Give this a video a view before you decide what to do. If you do go forward, please follow up this thread with your results both in the short and long term.

https://youtu.be/o690DovjDAc

 

If it were up to me, do several drain and fills until clean. A flush, like mentioned, will most likely have some negative effects. In the end, the parts are what they are. If they're damaged, no fluid changes or flushes will do anything.