2000 John Deere 6410 engine speed sensor

[sstrangford]

Good morning all! I have a 2000 JD 6410 tractor that I was feeding cows with on bumpy ground. Hit a frozen cow turd & the engine died for just a second then fired back up again and then died & has stayed dead. I can start it but when I let the key out of the start position & into the run position, it will not run. Tested voltage/continuity, etc on all the things. I've also replaced the starter, the ignition switch, the potentiometer & the engine speed sensor. After visiting with local JD mechanic, we decided it was either the fuel injector pump or the ECU. So we decided to send the fuel injector pump off to be rebuilt. Its a Delphi pump. Got it back, and messed with connections. Could get it to run but only at half throttle and the foot pedal & stick up on the console were dead. I could only run yhe throttle with the potentiometer. So, after doing a bunch of other stuff, I decided to run a temporary jump wire from the engine speed sensor directly into the ECU. Fired right up & ran. I could get full throttle with the foot pedal and throttle stick.Shut it off and started it up several times, revved the engine at various RPMs. TA-DAA! So, I undid the connections, ran a permanent jump wire and soldered them in place. Turned the key and NOTHING. The only thing I did was undo the connections at the engine speed sensor and the ECU.
If you've read this far, I applaud you. If you have any insight, I implore you. At our wits end with this and its our only loader tractor. Send help, send coffee & cookies or send a 100 grand for a new one.