F-150 died twice on freeway but started after it was towed

QI have a 1999 Ford F-150 with the 5.4L Triton V8 engine, automatic transmission and 4WD with 130K miles on it. I haven't experienced any trouble with my normal around-town driving, but in the last month I've had to drive the interstate twice -- and both times I lost power suddenly at 65 mph on the freeway, leaving me stranded. The engine died as though running out of gas. It took maybe 5 to 15 seconds before I lost my power steering. While waiting for a tow I cranked the engine -- it would start roughly and die immediately.

After it was towed to a shop they tried starting the truck, and it started right up and ran smoothly. They said fuel pressure was good and there were no codes from the computer.

The same thing occurred a month later, again while on the interstate. After having it towed again, it started right up at the shop. Please help!

AStart with the basics. The symptoms fit vapor lock due to high underhood temperatures? The fact that the power steering continues to operate for 10 seconds after losing power might indicate that the engine might still be running roughly and not immediately stalled.

Similarly, a problem with the fuel system may be allowing excess vacuum to build up in the tank. Safely open the fuel filler cap after it stalls, relieve any pressure or vacuum, and try restarting the engine.

If the fuel pump is weak, it may not be able to continue to supply adequate fuel and pressure to maintain highways speeds. Higher than normal amperage "draw" for the fuel pump is one symptom of a questionable fuel pump.

A clogged, restricted or failed catalytic converter can choke off exhaust gas flow, overheating the exhaust, exhaust manifold and cylinder heads causing the stalling. Put your gloved hand about an inch from the exhaust pipe outlet and feel for solid pulses of pressure. A shop can remove the oxygen sensor, install a gauge and measure exhaust back pressure. It should be 2 psi or less.

AThat's scary, for sure. A worn cup seal in the master cylinder is the most common cause of a sinking brake pedal, but now that your shop has tried three master cylinders, apparently that's not the issue. Can you duplicate this with the engine running but the vehicle stationary?

If so, a flexible brake line may be ballooning or swelling under pressure. This is detectable by holding each flexible brake line by hand and having someone push the brake pedal with the engine running.

Another possibility is fading front brake friction material due to contamination, wear, incorrect application or a lack of rear brake function.

I know you've had the brakes bled several times, but unless the ABS module is properly bled with the correct electronic equipment, air may still be trapped in the lower sections of the ABS valving.

QI am having problems putting the serpentine belt back on my 2000 Ford Escort Zx2. I finally found a diagram on the Internet but now am wondering if the rib side of the belt goes face down on the idler pulley.