"I replaced the fluid and filter with no result..."

If that was just a pan drain and refill, you only got less than 1/2 of the total 7.4 quart capacity.

Most here advocate a complete flush of at least 10 quarts thru the system. The procedure is in the 700/900 FAQ, see http://www.brickboard.com/FAQ/700-900/TransmissionAuto.htm#7XX940FluidFlush.

Volvo has recommended against the filter (screen) replacement since 1990. I'd say it's a non-productive effort, based on my few filter change experiences.

The kick-down cable can also affect upshifts — too tight (or sticking) will delay them, too loose (or broken) makes upshifts too soon.

It can be lubricated when disconnected from the throttle spool and support bracket, so the open end can be propped or tied up and ATF repeatedly drizzled down the wire.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.