I bought a '90 4Runner and the cabin fills with bad fumes and idles high. It runs well, no exhaust pipe leaks, but it is running really rich and smells of raw gas under the hood after starting. I thought it was an exhaust leak, but now I think it might be something else. I hear of vacuum leaks, any advice would be great. Im in Costa Rica and anybody with a toolbox a ratchet set is a mechanic. Can't trust them to fix what I don't know is the answer. Thanks!

 

Has to be holes in the firewall or the floor

Just old oil and dirt heating on the engine might be enough to cause your issue

your description of the smell is pretty vague .

To me Exhaust oil and coolant burning all have a very different smell

The best one was during the feud with my neighbors they kept putting all kinds of things on top of the catalytic converter talk about interesting smells

 

The hole in the firewall is my first hunch too after checking for exhaust pipe leaks. Especially since it is worse immediately after stopping in traffic. I am going to take it to a marginal mechanic and get it checked out. It may be a manifold gasket leak combined with a hole in the manifold. The smell is half burned gas, part exhaust if my olfactories serve me right. No rotten eggs smell, but I can taste it when I drive and it burns my eyes.
Your neighbor's story sounds lie a lot of diagnostic stories i've observed in Costa Rica! Thanks, I 'll keep posting.

 

Just get your head under the dash and look unless it is physically impossible for you to do.

 

Ha! Thats what i figured. Maybe stick a bright flashlight under the hood. I'll let you know.

 

Well the culprit for the gas smell in the cabin was finally discovered. It was the altitude on the mountain in Costa Rica. It ran very rich and the fumes were intolerable, but when I came backdown to 3,500 ft. It was fine. I remember that being the case with my old type 2 volkswagen. Crazy huh?