overdrive

Hi Guys!! New guy here, I just got my hands on a 2001 lesabre limited with 275000 miles on it (CHEAP Car!). The car runs and drives great with one small problem. The transmission doesn't even try to shift into overdrive. At 60 mph the engine is running about 2300 rpm. A "mechanic" checked it...

My 1994 base model has 157k miles on it, and started having problems with the transmission around 135k. At the time, I thought it was engine problems, because of the way it acted. But between trying a bunch of parts swapping with the engine that didn't help the problem, and tons of research, I...