2000 Saturn sl while driving just looses power bogs downs till you let off the accelerator I've replaced filter and temp sensor any thoughts on what might be the problem and the check engine light does or has not come on

 

I would still check for codes, but if it runs better at light throttle I would suspect a plugged cat converter. Restricted exhaust can be difficult to pinpoint.

 

I agree with Andy. The first thing I'd be checking is the exhaust system for a blockage or the cat or muffler coming apart on the inside.

 

You can pull the front O2 sensor and attach a back pressure measuring tool. I don't remember the spec but will dig for it if you want me to.