Recently bought a 95 T100.

When pulling up the driveway (400' drive uphill off the main road) and parking, there is a strong "rotten egg" smell. I don't notice any smell during normal driving.

Gasket of the O2 sensor behind the cat looked like it was leaking so I replaced it, but smell persists.

Muffler has holes rusted through from the inside along the bottom (probably water condensation).

Truck has about 85K miles. 100% stock engine and exhaust.

Any ideas?

 

It is you cateletic converter, all Toyotas do it. Do a search for suflur, cat, etc. There have been a lot of threads about this.

 

Switch to a different brand of gas. Some gas companies put more sulfur in their fuel than others.
Ive always had good results with BP/Amoco. No knocking, no sulfur smell and good fuel economy.
Cap'n

 

Amaco is the best in mine also, no sulfur smell. Texaco was always the worst.

 

This is kind of an old post, but if anyone searches it...

That very particular smell and a signifigant loss of power (more noticeable at highway speed) is exactly what happens when your catalytic converter dies. Typically a chunk of the element inside will break apart or loose, then plug/clop the exhaust. This creates a ton of backpressure against the engine and causes power loss. You might hear some jingling/rattling from under your vehicle, too.

 

As far as I know, there is one other thing which can cause it - boiling your battery by overcharging it (usually due to a bad voltage regulator).