1989 Mitsubishi truck

Change out the o2 sensor and the air cleaner element. Run a tank of super thru it and add 2 bottles of chevron techron product in the tank(double dose) good luck

If I was told there was to much fuel in the exhaust could it be the catalyic converter is plugged would that give too much fuel in exhaust at smog testing?

No the converter scrubs the carbons coming off a clean burn. The o2 sensor reads that exhaust mixture before it gets to the coverter and tells the computer to back off on the fuel its to rich down here. And vice versa for lean. The newer cars have o2 sensors before and after the converter to tell how good its controling thr carbons down steam.

Thank you very much. Much appreication for the help

Can anyone tell me were the inline fuel filter in the rear is located on this truck

The PCV valve in this truck is VERY difficult to replace. The entire intake manifold plenum needs to be removed (and everything on top of it) in order to replace the valve! But in a car this old, it has to be done to eliminate oil burning and smoke in the ehaust. The hose to the PCV valve is probably clogged also. Once I did this, I passed inspection with no problem. Good luck.
PS. I'm talking about a Mitsubishi Montero truck.