TLDR.
Drove from Salt Lake area to Lincoln Nebraska trailer in tow today. Left at 4 am and cleared the pass heading to Park City without issue. Through Wyoming the 7000+ elevation made the truck feel winded and EGT's were the gauge I had to drive from.
Cleared the 8600 ft pass between Lenoir(sp) and Cheyenne again without issue. But in Nebraska my torque converter started randomly unlocking again. I had this issue 10 days ago and replaced the FIPL. It hasn't happened since, 1600+ miles, but started again today.
That and the 90+ temps in Nebraska virtually killed any chance of efficient travel. With the sometimes constant locking/ unlocking of the TC, trans temps went up. Never let it get over 210. Engine was stuck between 210 and 220 and I couldn't pull the flats in overdrive without 1200+ EGT temps. Drafting a truck however, yeah that worked beautifully. Was the only way I could maintain over 63 mph. Yes 63 mph in drive, not OD, on the flats was 900+ EGT temp. Never seen anything like this before.
With the TC issues I had to stop twice to cool off the transmission. I should state I have an extremely large aftermarket trans cooler in front of the AC condenser and a gauge inside the truck. Without those, who knows what might have happened.
Anyhoo, after struggling 350 miles through Nebraska it cooled down to about 85. It's like a completely different truck all of a sudden. Trans goes down to 180, Coolant drops below 200. I can pull most of the hills in OD at EGT's below 1000. I couldn't even pull the flats before. All I can say is that I must have been thoroughly heat soaked earlier.
I had this truck in Texas back in 07-08. Never a problem like this. But it has been a while.
One odd thing I noticed while trying to nurse it along.
If I turned off the OD and drove a few minutes at high rpm, the TC would eventually stop cycling and when I went back to OD it would not happen for 10-15 minutes. I have no idea why.
Anyone have any ideas what may be causing the TC issues? I suppose the new FIPL could have failed already, but if not, what are you thinking?