Tensioners on your 2.5 SOHC are known to fail, especially after a timing belt. It will sound like a piston knock as the tensioner just flaps around under the timing cover. If I was you I would reset the cam timing and do a leakdown to see if there is any damage in the valvetrain or pistons. If no damage, then go out and get a new tensioner, put it in and you should be ok. But, with the problems you describe above it sounds like you've got some work ahead of you.