This is the stock 4.0 throttle body

As you can see it's a fairly simple unit with a couple of electronic doo-dads.

doo-dad #1 is the Throttle Position Sensor  (5234904)
doo-dad #2 is the Idle Air Motor (53007562)

Now for the most common problem, rough idle.  Let's take a look at the IAP (Idle Air Passage)

That little slot you see is the IAP.  As you can see it looks so-so but then look at the underside and you can see the goo that has been deposited.  This goo gets there because Jeep decided to ventilate the crank case by taking air from above your filter, running it through the engine, then dumping it back into the intake manifold.  Problem.... Sometimes the air goes the other way and sends oil vapor down the intake.  Even my old Chevy had a filter to keep this stuff out of the carb.  Anyhoo </soapbox>   Simply spraying the IAP every oil change will go a long way to keeping this problem at bay.  But there is another issue.  The goo that builds up will also affect the flow around the butterfly.  The simple solution is to take a toothbrush, spray the TB with cleaner and scrub with the brush.

So, watcha looking at?  Go get some TB cleaner that's SAFE for O2 sensors and SPRAY.  Your Jeep will thank you.

copyleft 2002, DougW
link, copy, whatever...