740 GL kickdown cable adjustment?

Its an 89 Volvo 740 GL sedan. B230F engine, non-turbo. Ever since I
got it, it shifts very late into third gear.... second gear is perhaps
a little late, but not bad. If I understand it right, if the kickdown
cable is too tight, the shift points will all be shifted upward to
higher than normal speeds. So I tried adding a little slack... then
more, then more. Now the cable in front of the threaded adjustment
hangs way down, and there are only about two threads left on the rear
side of the adjustment....so I have moved it almost as far forward as
it will go. It made very little difference. It seems to rev up less
before shifting into second. if you hold steady acceleration, it will
not shift into third until you hit 38 mph, and the overdrive does not
kick in until you hit 55. Way high on the shifting to third....am not
so sure about when the OD is supposed to kick in. What I do (always
have done) is "help" it shift by letting off the gas pedal at a
normal speed for the shift into third. It will then shift into third,
as soon as you let off the gas a little..well before hitting 38 mph.
So, is it possible that I just need a new kickdown cable, or does
it need adjusting at the tranny end (if any possible)? Or is the
tranny just messed up? Thanks!