Thanks - the Haynes and Chiltons manuals aren't the best, but that was all I had to work from. If the factory manual says 37 PSI is good then I won't mess with the regulator.

The fuel and air filters are new (fuel less than a month old, air a few months, no change when either was replaced). I've doused the area around the intake manifold with carb cleaner and noticed no change in the idle, so I don't think it's an intake gasket. I'm not sure where to go next. The check engine light isn't on, and no codes are stored. It just passed the OBDII smog check. But, nobody can figure out why this thing runs like crap. Any ideas would be greatly appreciated - we're tired of dealing with the problems, but financially can't replace it right now.