That sounds like a transmission problem. Is your " Check engine" light on?
Also, with 160K miles, has your trans ever been replaced?
You can drive your vehicle for at least 20 minutes on the streets (stop and go traffic), then pull your transmission's dipstick.
Check to see what color the fluid is and smell it also. If the color is anything other than red, then it's old and needs replacing. If the fluid smells burnt, then that's a good indication your transmission is going bad.