I have a 93 Ford Aerostar extended passenger van with a 4.0L engine. It has over 160,000 miles but runs and looks good although it does use some engine oil. Recently, I ran low on fuel, really low but somehow ended up back in my driveway before running completely out. The next morning my wife tried to start the van (I was going to tell her I needed to get gas first, but I slept in that morning). She cranked it quite a bit before I realized what was happening. Later, when I did get gas in the tank and started it, the engine ran really rough. I replaced the fuel filter thinking it may have clogged up on me. No effect. Finally heard a hiss sound and found vacuum hose came off for the brake booster and also a vacuum line going to the transmission area. Put those back on and engine smoothed out. But, the van has no power up hills, just quits when trying to go up an incline. Pressing accelerator just causes a roaring sound but no power. OK if I'm on level ground and not accelerating. Two different opinions from mechanics. One says I have a blockage in the exhaust, most likely the catalytic convertor. The other says the fuel pump is the problem. May have insufficient pressure or capacity. I tend to agree since low fuel started to whole thing. Do I have to drop the tank, or is there access from the floor above? Or is it something else entirely? Thanks!