91 xj AW4 won't go into overdrive sometimes it does and sometimes it doesn't at 4500 RPM. Already adjusted the kickdown cable and verified the transmission fluid quality and level. Have not replaced the tps and the nss is likely dirty as I have to start from neutral sometimes.

 

I believe there is a solenoid that controls the 3-4 shift. I could be wrong. Heaven knows I've been wrong before. If it is shifting sometimes there may be a loose connection to that solenoid or the TCU isn't seeing whatever it needs to make the shift.

 

Unless it's different to the AW4 in the 95 Cherokee, 4th is handled by both solenoids off. I'm wondering if it's possible that there's a sticking solenoid holding onto a lower gear.