1990 Transmission issue

I have a 1990 Olds88. Lately, the transmission has been acting strange. The transmission shift's too early... through all the gears too quickly.

This could be a bad vacuum modulator or a misadjusted tv cable or the cable is disconnected or broken.

Thanks for your reply

I just want add that this morning after the car warmed up, the car shifted better.

I guess I will go ahead and replace the Vacuum Modulator since it's a cheap part and easy to replace first.