My '90 Isuzu (4 cyl. manual trans) Trooper has an idle problem.
When I shift into neutral, (at a red light) the idle goes up and down from
1000 to 1900 rpms.
Up and down, up and down.
I just had a new head gasket installed. The shop said I needed a new oxy
sensor since the old one was contaminated. They said if I didn't change it
the worst would be the check engine light would stay on. I told them to
throw it back in there, and haven't seen the check engine light yet. But the
rpms sure do oscillate.
What do you guys think. How hard would this be to swap out myself, with
minimal time, tools and initiative? where is this puppy located?