MPG needs help and runs hot sometimes.

I have a '91 Laredo, 226K, 30X9.50x15 BF Goodrich All-Terrains, 2" lift, rebuilt motor with 80K, got hit by a semi last year and it sat for a year before we fixed the front body damage AND replaced the radiator, hoses, thermostat. I've also put a K&N filter in the stock filter box. Not only is my MPG worse than before, 15-17 before, 11-15 now, but it will also run temp. at about 260 when driving or idling on a warm day, was 230 always, before accident. Any ideas on either subject, PLEASE!

The temp sensor could be bad and what transmission?

Not sure of the tranny, AW4 maybe. 4x4 automatic. Also has new temp. sensor at thermostat block.

The temp sensor for the gage is in the back of the head.
The low mileage could be a bad TPS or Brake light switch, both can keep the torque converter from locking up.