i have a 1990 4runner 3.0. i get really bad gas mileage (12mpg). and when i start my truck after it has been sitting for about 4 hours or more it stumbles, smells like gas and puffs out black smoke. it does it when pushing the gas between 1500 and 3000 rpms. only when cold. im starting to notice some condensation also. when i push the gas down semi fast it will hesitate and stumble. im going to take a video in the morning and put on here (some how). everything has checked out ok.

just checked the 02 sensor and it was at 6.4 ohms. is this ok? im running out of ideas and its really frustrating me.

btw. tune up of plugs, cap, rotor, seafoam. all have been done Headgasket done about 10,000 miles ago by a 30 year toyota tech.

 

Check the FSM for the ohm specs.
http://personal.utulsa.edu/~nathan-b...01heatedox.pdf

Sounds more related to the coolant sensor
http://personal.utulsa.edu/~nathan-b...98engineco.pdf