Taking longer to shift from gear to gear

At first the only problem I had was the shifter would not allow me to take it out of park unless the release button was pushed, this comes and goes. Then it started taking longer to shift from gear to gear, this comes and goes. I have codes po498, 61-1, po141, po122. I know that po141 is an o2 sensor bank 1 and 2. I have checked my battery terminals and all is well for 61-1. I don't know what po498 is other than evap emission valve control. And po122 is something about the throttle positioning sensor. My gas mileage has dropped by 10 mpg. What should I do? Are these all separate problems or are they related?