Trouble code p1135 for the A/F sensor. I have a 2001 3.4L 4runner with 149000 miles. I just changed my timing belt, water pump, both belt pulleys, and thermostat all myself. Drove about 100 miles and everything was running great and then my check engine light came on. I have checked everything I touched while doing the work. Nothing seems wrong. I cleaned the mass air flow sensor and changed the air filter (pretty dirty). Could this be just a fluke that it the A/F sensor went out right after all the work I just did? Any suggestions? Thanks.