Installed new Ford T-stat, degas cap, Riff-Raff CAC pipe (old one had a hole), cleaned EGR, cleaned EBP, initial drain of older (60K) Ford Gold and refill with distilled water. Took it out for a ride and was still getting ECTs of 186 at 65mph. It would occasionally drop to 184 (coasting down hill) or climb to 190 (uphill - short not extended and not much incline). EOT stayed pretty constant at 192-194. When the ECT went to 190, EOT went to 195 but dropped back to 193-4 when the ECT went back to 186. Interesting because prior to the work above, I was getting differentials of 10-16 degrees pretty consistently between ECT and EOT.

Also, on WOT up incline, ScanGauge2 showed Boost going up to 27.1. Is that a bit high? Even after unison and vane cleaning, it has gone into limp mode once pulling a heavy. Should note that next WOT uphill, it only got to 25.3.

 

You should have put the 203 degree stat in while you were in there, that holds the temp around 195 most of the time, were you running the a/c the condensor throws alot of heat off, that could acount for so much changes in the temp. lots of variables the electric fan clutch coming on and off, if your looking for steady temp with the 6.0 good luck.

 

Put one of these thermostats in to get your ECT up.

Mishimoto MMTS-F2D-03H High-Temperature Thermostat

your boost numbers look normal to me. What caused the truck to go into limp mode?