So my 1997 4runner with 130k miles has been getting around 12mpg not normal at all. There is a sulfur smell that comes from the truck at stops. To me the bad smell and bad gas mileage means the cat is bad, but the engine is not reading any codes. What could be wrong? Thanks

 

Try replacing your 02 sensor, spark plugs, spark plug wires, distributor car and rotor, air filter, and fuel filter. All of these are items that wear out, and need to be replaced under regular maintenance.

 

Wheres the sulfur smell coming from. The truck runs like new

 

I would like to know the answer to this as well. I am up to date on all the regular maintenence items, but I am still getting that smell at stops. I get around 20 mpg though, so not sure your bad gas mileage and smell are related.

 

As I recall, the sulfur smell is quite common with our catalytic converters (Search to verify. there's a huge mega-thread talking about the odor. I believe the end thought is that nothing is wrong with the cat. it just stinks. brand of gas will vary the odor).

O2 sensor is in my future. you may search o2 sensor replacement. conventional wisdom has them going out < 130k you've got and without throwing a CEL.