88 Cherokee Pioneer Help

I need some help. We bought a cherokee and when I went to get it smoged it would not pass. I was told it was running too Rich and needed a new o2 sensor. I replaced that, but was told that made it worse. The Emission matin. Light stays lit on my dash panel now. Any Ideas ?
We have had alot of problems with this jeep. Due to the previous owner abusing it and never taking care of it.

Also we have a problem with it over heating. We noticed there was a hose with a T like connector coming from the Fill tank for the coolant that is not hooked up. When trying to find the part noone seems to know what we are talking about.

We have oil in our Air filter and was told it was the PCV. But then we are told there in no PCV and can not seem top find it anywhere.

Next is the air vents. It only blows out of the defroster vents. I love my jeep and dont want to part with it but my husband is tired of the problems. Anybody know whats up ?

TIA

About the T connector. My guess is the heater core is leaking so someone blocked it off rather than fix it.

No, there is no PCV valve. There are two connectors on top of the valve cover. The rear one is a vacuum line that connects to the metered orifice. That means where that vacuum line goes into the valve cover, there is a round 'disk' - that disk is supposed to have a hole in it, I think 2.8 mm in diameter. If that hole is plugged, and it almost certainly is on your vehicle, compression in the engine causes oil vapors to blow back into the air filter. They get there from the hose on top of the engine toward the front. THAT hose is supposed to allow fresh air INTO the engine, but if the oriifice at the rear is plugged, instead oil and exhaust vapors blow back into the air filter. To fix this, remove the orifice disk at the rear and drill out the hole so that it is clearly open, then replace it. Incidentally this will also cause oil to leak out the engine's rear seal.

Air vents. Most likely a vacuum line problem. This can be hard to find. I would suspect it is linked to the fact the heater core is disconnected also. The controls operate vacuum valves.

The emission check light should have been reset by the person who installed the O2 sensor.

You have a lot of problems. Some of it sounds like vacuum leaks at various points. Does the 4WD work properly? That is vacuum controlled. I recommend you get a Haynes and/or Chilton's book and start learning about 'what's under the hood!" That is, if you plan to keep the vehicle. None of the problems are terribly expensive to repair, even the overheating problem.

Ed

Yes the 4wd works great. No Problems with it.
I will check that hose tonight and hope it works. I was being lead to believe that I had to replace all the hoses. If I can drill it out for now I will. Thank You
Sheri