Some problemos. Tried to fix, but nope...
Alright then. Got some engine trouble, I've done the forum searches and to no avail, got nothing.
So my check engine light comes on for about a week at a time, and then goes off for a couple days, then returns. Took it to a mechanic and they checked the code, all I got was that they said it was a "Soft"(Or did they call it "sub"?) code, so they reset the computer and sent me on my way. Well the check engine light still comes on at the frequency I described above.
While the check engine light is on, the vehicle doesn't idle well, it sounds like its dropping and raising RPM's. Now the first thing I did was take apart my throttle body, and cleaned the IAC valve. It was very very dirty and caked with crud. I cleaned everything associated with the throttle body very well, and reattached everything the correct way, and the jeep still has this problem of not idling well and the check engine light still comes on.
When the check engine light is off, it idles a little better, but I still feel some soft knocking. I also get some pretty horrendous gas mileage. I know my WJ isn't supposed to get great MPG's, but it seems to be way below par. About 12-13 MPG with mix of city and highway. I've been doing my best to drive like a grandma, but still get his horrible mileage.
While in motion, the engine runs fine, and it seems to have the appropriate amount of power.
The fuel system was cleaned recently, the air filter replaced, engine oil changed with new filter and correct oil and amount.
It's a 2000 WJ(Of course) with the 4.0, about 134,000 miles.
I like to consider myself a budding home garage mechanic, but I do not know what else to really do or check to fix this problem.
Thanks in advance for any future help or insight I can get.