1998 Ford F-150 • 110,000 miles

I bought his truck, 1998 Ford F-150 4.2L Supercab, two years ago. We've only used it for short trips for the last year until yesterday. I drove it through mountains, a four hour round trip. I didn't have any problems for the first half of the trip, but when returning I started to feel a total loss of power climbing mountains or on long, fast straightaways (60 mph). The power would cut about every 5-10 minutes when I pushed it (going up mountains or fast straightaways). The engine would continue to idle but no power when I hit the accelerator. On the first occasion it stalled. When I restarted the truck, the power returned immediately and all was good for awhile, until we started climbing again. After the first loss of power and subsequent stall, I just turned off and restarted motor in neutral for subsequent power losses. The restart always restored power.

At first I thought maybe we were sucking wind, so tried to tap out the air filter. It's not uncommon to clog the filter because we live around a lot of dusty, dirt roads. I knocked some dust out, put it back in but same problem happened again. Not convinced I could rule out the clogged filter, I removed it for a stretch of paved road (no dust there). Problem still returned after doing some mountain climbing and hilly up/downs. At this point we were driving slower so I could hear some "popping" concurrent with the loss of power. I wondered it it was some kind of spark or something but worried after reading about a coolant leak problem through gasket from this year/model of F-150.

We still have no problem on short trips, but if it's the gasket problem, I've read we need to get it to a mechanic right away. Problem is in our country, Honduras, there's no end of untrained mechanics. I'm an American running an orphanage here, so hoping it's not the coolant/gasket problem, which could result in replacing engine.
March 3, 2012.

If the truck has sat it could have bad gas in it and it turns into a varnish like substance which will clog fuel filters and injectors. The other posibilities are intake and exhaust tract restrictions . When going on short trips the exhaust will not always get all the water that condenses in it out and it will rust. Check the intake tract and then check the exhaust. Mostly look at the catalytic converter. They can rust inside and fall in on themselves and look okay outside. Bang on it with hand or rubber mallet and listen for loose material.
I am going to give you a diagnostic walk through as well. It goes into a lot more detail than I can here. Just follow the links below;

Thanks! Come to think of it, I bought gas in middle of trip. I didn't have problems before that. It's very possible they sold me bad gas, which is not uncommon here, unfortunately. Neither food nor gas is tossed here when it becomes bad. It sits on the shelf or in the tanks until it is sold.

Would that make sense? Buying bad gas? Again, I only had problems when climbing mountains and speeding down straightaways. When I tried to rev the engine, nothing happened except I heard the popping the sound.

Mar 3, 2012.
Actually, my wife used it today for our normal short trip into town. She said it lost power at a traffic light, so she restarted it and was able to go.

So still wondering if/hoping it is bad fuel from last fill-up. If that is the case, should we hastily drain the fuel? Or will it be OK once this fuel is gone? Should we add some kind of octane booster or fuel cleaner to current tank?

Mar 4, 2012.
No I would not drain gas. You might want to change the fuel filter if the truck has an inline filter. If the truck sat the gas turns to varnsih quicly and once you run the truck it can then clog up thing like the fuel filter.
Otherwise the diagnostic walk throughs will cover all the points to help you find the problem.