I just picked up a '99 Lariat 7.3. It runs fine just putting around, but it won't boost up properly. As long as you're just driving normally you don't really notice, but if you floor it to pass someone there is just no extra power. It doesn't smoke or make any weird noises. No blowby in the engine either. My buddy is a Ford tech, but usually only works on 6.0s. He dropped the tank and replaced the in-tank sock and says he checked the turbo as well. He doesn't know what else to do without throwing parts at it. Said the fuel pressure at the engine is fine as well.