Automatic Transmission problems
Last night, I was driving and missed my turn so I pulled into someones driveway which was at a steep decline and put it in reverse. When I went to back out, it didn't go back. I eventually had to floor it and it jerked into reverse and finally backed up. And when I'm driving up hills, it wants to slow down about 5-10mph (depending on the steepness). I checked the fluid, it's the right color and smells good. And I checked my codes, and the only one that has shown up is P0420. Bank 1 cat on the threshold of low efficiency (if I remembered all of that correctly). What should I look at and where should I begin to correct this issue?

