It does sound like an elevation problem to me. If not then it may be your sensor. There is no reason for it to start hard either. My 01 turns over about 3 times and it's running even in cold weather.It has 70,000 on it and I replaced the plugs at 60,000.
Make sure your air filter is clean and that your PCV valve is working.Also may want to have someone check your fuel filter.Run some Techtron through the gas tank.
Let us know what you find out. Good luck at your new home. Mike

2001 Toyota Tacoma 4x4 SR5 auto trans, ext cab,16" Good Year Tracker tires and 2.7 4 cyl. Love it!!
Mobil 1 5w30. Valvoline 75-90 syn in front and back differential ."Keep the shiny side up and your trash out of my woods!"