1992 Ford Tempo 92 Ford Tempo rattle

I have a 92 ford tempo with a rattle, and the engine smells hot. The rattle is coming from the pulley tensioner, Any ideas? It sounds like cards on a bike wheel and I replaced the pulley tensioner twice, and it is still jumping around, I also replaced the belt. Some one suggested the A/C pump pulley, and someone else suggested the idler pulley. Please anyone with any ideas? I am stumped. While it was sitting in the drive way, idling, a big noise like a starter grinding and a big ploom of white smoke came from under the hood.