Hi all, I recently replaced the 5.9 cummins in my son's 2007 Ram 2500. It has the 48RE Trans. The truck will shift into drive and rev fine for several minutes then nothing. No funny sound, no vibration, just like its stuck in neutral. If I shut it down and restart it does same thing again. Shifts fine then nothing after several minutes. Fluid level is good. Not throwing any codes. No check engine light. Engine runs smooth and has power when first started. Revs like in neutral when in gear after few minutes. Is something causing it to go into limp mode? I have read that when in LM the truck acts like its in 2nd or 3rd gear with no upshift into OD and revs high. This truck will not move at all after it acts up. I am using an Autel MaxiDiagElite code reader. Trans ran fine before swapping engine which is a reman long block. Any ideas? Thanks.