Idle problem 1999 Rodeo 3.2 automatic 2wd

Hi, hope someone can help.
I have a 1999 isuzu Rodeo 3.2 6cy, automatic 2WD with 107000 miles. The engine suddenly began to idle @ 2000 rpm. No check engine light.

I have replaced several devices such as, the ICV idle control valve, four 4, co2sensors, EGR sensor, and the Mass Air sensor. After each item was replaced the engine ran at a low 800 RPM for a day or two and then went back to 2000 RPM idle. On none of the occasions did the check engin light come on.:banghead:

Vac leak. IMG.

I agreed.

Thanks FL 3.2
Can you elborate on the vac leak MIG. I have checked all of the lines that I can see. What is MIG?

What is MIG?

What is MIG?

MIG=Manifold Intake Gasket. This is very common failure on our truck per Amigo-2K.

Look in the faqs for intake manifold gasket leak.