Speedometer Not Working When First Starting Off

[dstrick32]

94 Toyota Ex-Cab 4X4 3.0 Auto Electric Speed sensor
My speedometer will not work when first starting truck. Odometer works, transmission shifts ok and no codes. After it does start it works fine until the next time it sits for awhile. Short stops don't seem to affect it only prolong stops. It first started working shortly after starting, within 2 or 3 miles but now sometimes it may go 30 miles before it will start working. After it starts there is no bouncing or erractic moves works smooth. Anyone ever had this problem. I figure speed sensor works correctly since odometer work when speedometer doesn't, transmission is getting readings from speed sensor because it shifts correctly and speedometer works correctly after it decides to start. It's sure puzzles me!! Any ideas??