No power, engine bogs down

Engine developed problems about one hour into a 2 hr highway ride. Engine loss power and rolled to a stop while engine remained running, but as soon as throttle was pressed, engine began to bog down again and was unable to continue. Towed it home where I checked the following items. Fuel pressure is ok, within pressure range, 40lbs with engine off, 35lbs
at idle. With vac removed from fuel reg, pressure went to 43lbs, so assuming pump and regulator and filter are ok. When car is shut off, pressure holds for at least 30 min before starting to drop, so I think fuel reg and injectors are ok. I checked the map sensor, get 4.8v with key on engine off. If I create a vacuum it drops to 2.8, so that seems ok as well. Do not have test equipment to check mas air sensor, so I replaced it with no improvement. I also loosened the exhaust manifold to check for clogged cat, but that did not help. So I'm out of things to check. Any help would be greatly appreciated.