I have an 02 osb with 85 k miles. I change the oil religiously with synth, good filters and just had the timing belt replaced. Before the timing belt change I kept getting a check engine light and the code says PO328 Knock sensor high input bank sensor 1of1. (this isn't why I had it changed, just for peace of mind). Anyway after the change, the check engine light is back. Performance is crappy. Any suggestions?

 

Try changing the knock sensor? It's not an expensive part and they do go bad.