RPMs getting stuck

[c1983]

Sorry if this sounds like a stupid question as I don't know much about cars. I've got a 2000 Ford cougar (auto) and notice sometimes the rpms get stuck at about 3000 (speed 60km/hr-70).
When it happens I take my foot off the accelarator the speed drops but rpms stay the same, if I brake it feels as though the wheels lock up. The other day when this happened I noticed the traction control light flashed a couple of times.
Known problems with the car - front arm bushes are worn, it needs new rotors (brake warning light has been on for nearly 4 months now) but the brake pads are fine and the battery warning light comes on sometimes
Just wondering if anyone has any ideas what might be the problem .
(taking the car in for a service tommorow.