GOt a few questions- I have a 1991 7.3 with the E4OD. I was on the highway last night doing about 74-77mph up some gradual hills in Vermont. The first 30 min of my trip felt fine no problems. After that I could feel the trans acting up. The tach would rev up from 2400 to 2700 rpm than drop back down. Itd do this for a couple time than stop. Is this the torque converter locking/unlocking up the hils or is it slipping? It only has maybe 15000 on the trans. Thanks

The trans and TC are reman-d units from ford installed 3 summers ago. Running the spec'd fluids and was not hauling any load

 

Follow up- I went for a short 5-6 mile drive todayt and had the transmission act the same way. I was doing 40-45 mph. What could this be? I smelled the ATF fluid but could not definitively say it smelled burnt. Any ideas?

 

probably the converter unlocking.....hopefully that's all it is.
this must be the '89 in the sig? is that an oem unit or has she been reman yet? how many miles?
didn't take a peek at the solenoid plug yet?

 

yeah that is the converter unlocking and locking back up.