Cummins 605/2050 immediate RPM drop issue

[tree98]

I don't think your problem is programming related. Have you taken the air cleaner out and inspected the piping looking for restriction of some kind? What's the max it's boosting? Maybe take the tube off of the crankcase breather box (not sure of the actual name) maybe there's something in there restricting flow? Just seems like a flow restriction somewhere.