I started my jeep up to warm it before I had to go to work and with in 2 minutes It really blackened the snow on the ground. Is this because my jeep is running rich. I also have a small rough idle on the jeep.

 

Im no expert, but ill try and help you out. Maybe you have a dead spark plug and that extra fuel is just being throw out the exhaust. check engine light on? does it come on after a minute or two of the jeep running?

 

Black exhaust/ excess soot it usually a sign of running rich. Multiple things can be the cause, bad plugs, dirty injectors, throttle position sensor, low compression. Start simple/cheap first. Pull the spark plugs (if not familiar, google can help),needed replace, cap plugs,rotor,wires together spend the extra couple bucks and get brass terminals, run your fave flavor of injector cleaner ( I like seafoam to start, put in with 1/4 tank or little less and drive it hard) next fill up run some lucas injector cleaner, a search on here will tell you the steps to test TPS, for compression you can rent the tester from oreilys etc for free. Testing one system at a time will lead to good info which leads to good decisions.

 

There is no check engine lights on at the moment. I do have a rough idle as stated before. I was going to change the oxygen sensor, but I wanted to clean my throttle body first and see what that does.

 

What year is your Jeep?

 

Could be a leaking exhaust manifold as well.

That would let less gas pass the o2 sensor making the ECU think its running lean.

Lots to check.

 

It is a 97.