I've tried to use the instructions on diagnosing the transmission, but I'm obviously not reading them right or they are worded, out of order.

My car stopped shifting into high gear, the shift from 2 - 3 is real hard and I'm reving to 5k going about 55-60mph. I was just going to trade it in this coming week now I'm scared they wont take it. I checked the fluid, its dark. I noticed alot of fluid on my exhaust near the cats. I changed fluid and added some stuff that is supposed to help shifting.

the instructions say to drive and warm up. then turn off and put trans in "D". I cant shift to "D" when ignition is off. So I try to turn off in "D" and go through the steps turning "manu" on and off as I shift down, then hit the gas pedal and the "POWER" light is supposed to blink, but it doesn't.

help me I don't get it.