I bought my truck a week or so ago, and it never comes up into the 'normal'
operating temp, It will move off the 'C' and sit between the 'C' and 'Normal'.
It also misses when reved up over 3500rpms under heavy accelleration.

it has 65,000 miles, Oil & Tranny coolers, E4OD and the 3.55 rear end.

Im guessing the previous owner either removed the thermostat or
put in a 160 degree thermostat. Anyone else have any idea's on this?

 

I've found Ford T-stats seem to fail in the "open" mode. Replacing it would be a good place to start. As for the miss, when was the last tune-up?

 

It has a new airfilter in it, dont know when the last tune up was done Ive
had it for <1000 miles, guess ill pull the t-stat and take a look at the plugs/wires/dist-cap.