2003 Ford Windstar EGR hoses

We have recently bought a 2003 Ford Windstar van, used, and it started losing power when you accelerated. We had it diagnosed, it showed it was the egr sensor, so we replaced that and it didn't help. Had it diagnosed again, the catalytic converter showed up this time, so we had that cut off. Still didn't help. Another diagnoses, by a different person, showed the spark plugs. So we replaced the spark plugs and plug wires. The van seems to be running better now, but the egr hoses keep popping off. We have put new hoses on the egr also. So the question is, why do the hoses keep coming off the egr? Thank you.