Start with the basics:

Plugs, wires, cap & rotor.
Check the timing.
Check the compression.
Check the vacuum lines.
Check the intake tube for leaks.
Check/change the fuel filter.

After that, just accept it is a 2.6 and your description is kind of what they do when they are required to go up hills. <img src="/forums/images/graemlins/smile.gif" alt="" />

Good Luck,
Michael