I have a 2003 F250 w/163,000 miles, all stock except EGR delete. RPM reaches 3000-3500 before it shifts gears. This started after I changed the transmission fluid and both transmission filters. Any ideas on what could be causing this?
I forgot to mention that the slow shifting occurs at WOT. The rpms reach 3000-3500 before it shifts gears. I've also gotten DTC P0238 three times when attempting WOT acceleration. The CEL turns off on its own after a day or overnight.