670 VNL - 2012 - iShift issue with DRIVE = D

Hi - the issue is that in DRIVE - the truck looses power with Gas Petal pressed to floor -
when its in reverse it seems to be ok

** I give it Fuel in D=DRIVE and it will not take off - just for 20 feet then its like it looses power???

Also no system errors in Dash - no fluid on ground - trans is dry ?
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NEW INFORMATION >> LOOKS LIKE THIS IS ANOTHER ISSUE - THE ENGINE WILL NOT REV - SO IN NEUTRAL - IF YOU PRESS THE GAS - IT WILL REV FOR A SECOND THEN - PETAL WILL GO TO THE FLOOR - WILL NOT MAINTAIN REV -- IF I DRIVE 5 MPH IT WILL
MOVE BUT IF i TRY AND ADD FUEL - PRESS PETAL - THE PETAL GOES TO THE FLOOR. NO POWER --

WHAT DO YOU GUYS THINK THIS IS?

Thanks

 

Mr NasRiza - it was indeed a derate issue - after turning power off in the battery-box
and further unhooking the RED power to batter - waiting 10 min - and
truck Powered back to life - as you recommended.

Thank You