The first thing I would ask is if the transmission fluid level and condition have been checked. If you haven't, that is where I would start. It could be low on fluid.
Here is a link you may find helpful:
Also, if the check engine light is staying on, have the computer scanned to see if there are any codes related to the transmission. Most parts stores will do it free of charge.
What you described sounds like either a fluid issue or a line pressure issue. Has the transmission been serviced over the years? A partially plugged transmission filter can lower fluid pressure. Also, there are pressure solenoids can fail. That is why I'm recommending having the computer scanned.
Let me know.
Wednesday, November 9th, 2022 AT 7:35 PM