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1992 Ford F-150 4X4

My Ford truck has a problem two mechanics have not been able to solve. It runs fine as long as it is on flat ground or going downhill; however, as soon as I go up a sustained incline, like going up the mountain to my house, it starts pinging loudly and then it looses power and starts to buck and shake wildly. If I give it more gas, I can get up the mountain, otherwise, it would probably continue to loose power. Its had a complete tune-up and the last mechanic said he experienced the problem, but couldn’t get it to replicate it on flat ground or in the shop and couldn’t look at it as he was coming up the mountain. It also eats gas, about half the mileage it should get, but not sure if that is connected. Its been going on for about 5 months and I’d like to get it fixed. Please help w/ any ideas.

Has there ever been anything done that is related to the distributor; ignition module, remove and replace for whatever reason, rotated for whatever reason, etc?

This truck should be a TFI-IV vehicle and ignition timing is critical on them.
When setting the timing, the SPOUT connector near the distributor MUST be disconnected. Failure to do so will throw the timing off by a mile, which will in turn cause poor running under a load, bad mileage, and pinging.

Hope that helps.

If one wants to put an additional load on an engine while one drives on flat ground (to simulate hill climbing a hill, or grade), one simply presses the brake pedal and gas pedal, simultaneously.
One would want to do this test, with a fuel pressure gauge attached to the fuel line/rail, and visible through the windshield/window.
Here are more details on fuel pressure tests (plural):

Is this problem coupled with a difficult to duplicate situation? Please list exactly what has been tested and what theories have been explored. Anything wild like a temporary gas tank or operating the truck with the cat. by-passed?

I don’t like to start out with the wild ideas first (you can get caught up with thinking a easy problem is a stumper) so let us know that all the basics have been done, better done more than once.

Any idea why the mechanics are having a hard time? is it because it is difficult to duplicate?