I had a similar incident happen driving down the highway my car went from 70 miles mph to 40 mph without letting off the gas pedal, I had to take my foot off the gas cause I couldn’t get it to accelerate back up to 70 so I had to put my hazard lights on and let it work itself out.
Yet you did not get a CEL?
Auto transmission or (if manual trans) clutch could be slipping. Does engine rpm seem to slow corresponding to slowing vehicle speed, or does engine rpm stay the same as the vehicle speed drops?
Note: We here at Car Talk forums are not able to see the post to which you refer.
Yes it’s an automatic, the rpms make it rev higher and the acceleration won’t go up past 40-45 I couldn’t accelerate past that because it was stuck in the high gear?
The transmission was likely in limp mode; reduced to 2nd or 3rd gear. The transmission control module will put the transmission into limp mode when certain faults are detected.