I recently got a 2004 focus zts and I decided I needed to change my transmission fluid judging by the color. I also changed the filter since I wasn’t sure what condition it was in. I thought everything went pretty smoothly but after I test drove it, it was struggling at speeds above 40mph. It was changing gears too fast and for no reason. After a little bit the O/D light started blinking yellow so I pulled over and started checking things, the fluid level is good I checked it on level ground. I’m trying to figure out what could be wrong, it’s never had any problems like this before I changed the fluid. I’m wondering if it might be the speed sensor, I had to unclip it and reclip it in replacing the filter. If I didn’t do it properly could it cause this problem? Has anyone else had anything similar to this happen after a transmission filter change?