yes, done all that, even went as far as checking the wires under the dash and so on

 

Also, you might what to pull the column covers and look at the OD wires leading off/out of the shifter.. The can at times rub and/or cut through on the column/ brackets.. After a full range of shifter action over time, some have rubbed through.. You can also check for power at the shifter connector there as well, to eliminate a possible OD cancel switch too..

 

I had a simular problem, took it to the dealer and they found that the wires to the fuel heater on the fuel filter had shorted together. Don't know if this will solve your issue, I know it's a strange place to look.