700R4 does not use a kick down cable, it is the TV (throttle valve) cable and it sounds like it's adjusted too loose. Make sure you have the correct cable installed and properly adjusted, plenty of discussions on here that elaborate on adjustment if you search. Also if your final drive ratio and tire size is geared too high you will experience fast upshift and lockup. Lower gear ratios help improve the use of overdrive and lockup but if you are just putting around town and not at cruising speeds, you may want to leave it in drive instead of overdrive until you are at cruising speeds.