96 f150 overdrive kicks in and out 40 - 50 mph doesn't doit with overdrive off. Then shifts real hard od flashes. Already changed that manual sensor on tranny help fluid is fine and filled

 

Mine did this and I had to get it rebuilt. It wouldn't shift into overdrive and the light was blinking. My guess is the gear or sensor for overdrive is going out or something. There isn't really anything you can do to band-aid it that I'm aware of

 

I have an 87 and mine did that to trans-x loosend it up enough that I just put it in drive and got the rpms up to about 6500 and it finally shifted and hasn't done it again

 

x2 probably going to need a rebuild, sorry.