...Is there a difference between A/C on and off? My A/C is fouled up and not using it making it run poorly. (That's tough here in Memphis.)
I was in a similiar issue (maybe not as bad) with a bad accesory belt pulley. That thing got shredded after the bearing failed!
When was the last time the pulleys for both belts replaced?
With all else you've listed the last other thing would be faulty fuel injectors.