Even so, your cat can still be bad.

Take it to an exhaust shop and have the cat pressure tested (I think).

 

Check where you buy gas
plugs/wires/cap/rotor
Cat
Your driving habits- Yes, even babying it can result in poor mileage in some cases
Your tires
For the actual coolant temp to read 183*, that's about right. At least that's what my OBDII scanner reads. Maybe run some injector cleaner through, and reevaluate your gas buying choices. Remember, even Texas gets a different blend of gas this time of year that not one vehicle performs well on. Outside temperature plays a role too. I've found that there are sweet spots in the weather in which my truck runs better and gets better mileage. Seems to me that the 40-45*F range works best for mine, but it could be different for you. At the moment, I average 11.5-14. All depends on what I'm doing.

Never forget, city driving in these trucks (well, any vehicle) wrecks havoc on MPGs.

 

hes got a 195 tstat and the sensor its rearing 183 ... to me the sensor its a lil lazy ...by saying that the sensor its taking to much time to get up there and engine running richer longer than it needs to

 

Just because there is a 195* thermostat in there doesnt mean that the truck is gonna run 195*.

 

I try to mix it up, never go to any off brand places. I run injector cleaner every 3-4K. Brand new 265 BFG's all terain. I know plugs are new, wires are napa belden. I dont know how old the cap and rotor are. When I first got the truck, the screws were loose, and I could wobble it left and right. Might of fouled it out.

 

Those big BFGs will kill your MPG, too.

 

case in point, i have a 195 and at speed, i run just about 210

 

Another thought, how are you calculating your mileage?

 

195 means that the tstat is starting to open at that temperature if hes not even reaching that temperature how did he even purge the system when he did the plenum

 

thats how its suppose to be