Poor Gas milage engine dying at start oir take off

I get 14 to 15 MPG around 3400 ft when I get into the mountains of Colorado I get around 19 MPG, no I'm not resetting going down hill. at 3400 ft the absolute pressure is showing 26 when the weather service is reporting 30.6 this is with the jeep shut down with the dealership data logger hooked up to the jeep. they replaced the mapp sensor or (absolute pressure sensor) other than cracked exhaust headers. this shouldn't affect the sensor reading while its shut down. Any idea what could cause the sensor to read so far off? The engine hesitating and dying at a take off. Dealership didn't know about the cracked header until I researched the problem and ask them to check under the heat shield. what is the range of the absolute pressure sensor (hi N low readings) under the hood (engine compartment gets real hot)any additional information would be a great help.

Wish I could help you out but I have to say, even at the low end, you're getting way better MPG than me at anytime. :crazyeyes:

Thanks Eddie
I'm trying to find out the parameters of my sensors. I don't think I should have better gas mileage in the mountains than at lower elevations and flat lands. Here is what I'm running. 35in Toyo's open country MT'S, 4.88 gears, Airaid intake, 6 speed manual transmission. Can you point me in the right direction for what the mapp sensor (absolute pressure sensor) difference should be?

Thank you for your input along with all the help you given me.