TRANS CHATTERS WHEN SHIFTING INTO OD

4X4 WITH 4R75E. AT 47 MPH THE TRANS CHATTERS WHEN SHIFTING INTO OD. ALSO, DASH DISPLAYED " REDUCED ENGINE POWER" AND THE TEMP GAUGE WENT FROM NORMAL TO IMMEDIATE PEAK. STOPPED AND PLACE IN PARK. TURNED OFF, MADE A CALL THEN RESTARTED AND TRANSMISSION DOING THE SAME THING?

More detailed history. December 2010 the trans would chatter at 47 mph while shifting into OD. This would happen at different times. Took to Ford garage. No codes and no drive issues noted. When temperatures dropped the chatter came back and suddenly stopped shifting into OD. A friend is ASE Ford mechanic and has been building all types of trans for 35 years. He removed trans and disassembled. I was there. What a mess. Sun shell, planetary, and TC all melted down. He rebuilt with heavy duty off road competition kit. New everything including new case and new updated valve body. Anyway, after system relearned the trans shifted ok. Now, the weather is cold again and the chatter has started again. Also, the dash beeped and the display showed " Reduce engine power " and the temp gauge peaked to max. I immediately pulled over in town, parked and shutoff. Made a five minute call and started the engine again. The display had cleared and the temp gauge had returned to normal. Drove it home and parked it. Please help. What is going on. My friend is in his late sixties and is asking for help. No codes displayed and again shows no drive conditions noted. He is retiring soon, but, wants to help me. He is puzzled and is asking for help.

Thanks :-)