1996 chevy silverado check engine light - code DTC P0175

1996 chevy silverado 5.7 225,000 miles, the service engine soon light comes on then it will turn off the next day and so on, connected a dtc code reader and it says P0175 bank 2 too rich, wondering what makes this code show or what does it need to repair. The truck when first start it starts with very high idle, it lowers when driving in highway or maybe can't tell the difference so if anybody can help me with this problem I will really appreciate it thank you.
hey silver10 this code will set if bank 2 of your engine is in fact running rich, however with that kind of mileage on your truck the problem could very well be a faulty oxygen sensor ,it could have the dreaded worn valve seals that all small block chevs are prone to . have you pulled the plugs to check their condition what other maintenance or repairs have you performed recently ........give as much info as you can hope this helps ...Todd