98′ Mondeo V6 Gear damage???

Hello Leutz! I have had the following problem for 3 days and need your opinion very much: If I start my 98′ Mondi V6 automatic cold is nothing, but if I am 10 – 20 min. on the road and then drive the car in the range between 140 and 150 (also quite briefly enough already) the buck starts to spin. It sometimes turns not higher than 4500 turns (hears and feels as if you chase it in the idle speed limiter, which is there with the automatic). he doesn’t manage to switch to the 4th gear or he doesn’t switch down anymore. Then he switches back to the idle and after eternal seconds first, sometimes he pushes the gears in the strongest way. Or if I am over 120, and he just jumps and jumps, and I insert the 2nd gear manually, nothing should happen, but he switches to the 3rd and mostly (not always) at the corresponding speed (as it should be in driving stage D) in the 4th. Although the selector lever stands at 2. Below. of 80 he purrs like a kitten, so drives without problems… Even if I don’t spend my highway ride faster than 130 there are hardly or quite rarely problems. Momentary mileage 139,000 KM. I would really be happy about numerous information and help, because I am dependent on my car… (drive over 120 KM a day) Maybe someone from you has experiences with it. Thanks in advance