My 3.0 gets poor gas mileage (9 mpg mostly on highway) and has poor power (even for a 3.0). It seems to run smooth, just low power. It's been recently rebuilt - completely.

I have set the timing, changed the knock sensor and cable, O2 sensor, plugs, wires, cleaned the throttle body, and checked for vacuum leaks.

No codes.

What is the likelihood the converter could be the problem?

 

is it glowing red after you drive it? that's a dead giveaway that it's clogged up

 

Never looked, but I'll check the next time I drive it. Thanks

 

Since the converter is downstream, the only way it could cause anything would be if it was REALLY clogged and raised the back pressure. Doesn't sound like the place I would start looking. (Glowing red could also be retarded timing, but in any event it is a 'bad thing.')

It is hard to imagine how your mileage would be so low unless you were running really, really rich. Smoke? You can check the mixture more-or-less directly by watching the O2 Sensor. http://personal.utulsa.edu/~nathan-b...01heatedox.pdf