740 transmission shifting erratically

[NZbuilder]

I have a 1992 volvo 740 non turbo automatic transmission. It feels like the transmission is always trying to change down gears the decides not to. It is worse at highway speeds but you can still feel it at low speeds. I thought it might be the overdrive relay clicking on and off. I have replaced the relay and still the same problem. I adjusted the kick down cable and it didn't change much. It's random and happens most of the time but other times it's fine.

I have checked the transmission oil and it's pink and at the right level so I think that's fine

Anyone got any other ideas of what could be causing my problem or anything else I could check?

Thanks for your help

[mtd240]

Could be the overdrive solenoid.

Replace with the IPD bypass kit if you don't ever need to hold the car in 3rd gear (towing), or if you want to save some $$