My 1993 3.0 pickup will intermittently stop shifting properly and cause the truck to jerk and sometimes stall. When this happens the power switch light starts to blink. Occasionally I can shut the engine off and restart while moving and the trans begins to function properly. I ran the diagnostic routine and the result was a bad speed sensor. I changed the speed sensor on the trans with no improvement so I bought a used instrument cluster and that didn't fix it. Because the problem is intermittent I'm thinking maybe a relay or lose connection. Any help would be appreciated.

Could be several things. Check battery voltage as well as grounds, make sure they're clean and bare metal.

If no stored codes are present, I'd drop the pan, do a flush and fill, and assess the health of the trans.