Background, my CEL on Buster came on awhile back.  I couldn't get a code on it.  I reset the CEL (along with checking fuses and wiring) and finally got a code out of it which indicated it was O2/Cat related.

Update, I pulled the down stream O2 sensor and discovered it was heavily carboned up.  It occurred to me I had not pulled it after I had done some catalytic converter repairs and had installed a new upstream O2 sensor.  So I sprayed the O2 sensor with some brake cleaner and blew it dry with some compressed air.  It cleaned the carbon off nicely.  Reinstalled the O2 sensor and.... so far, no more CEL for well over a hundred miles now.  MPG is starting to improve = I'm up to 23MPG.  Don't know if this is the new MPG or if the computer is gradually adjusting OR the winter fuel blend is at the pump now and Buster's MPG always decreases in cooler weather.

Also I'm still wondering if my EGR valve could be part of the over all issue (carbon fouling/caking).  Has anyone had any experience with their EGR valve carboning up in their 2 liter engine?  I know the 1.6s had issues with this, but I have not, to date, heard about a similar issue with the 2 liter engine.  I'm occasionally experiencing very low idle at stops, which would kind of indicate a vacuum issue AND Buster has suddenly been needing about 1/4  quart of oil every 150+ miles but this has been irregular too.  I checked the PCV and the PCV line.  They are clear and there is a vacuum when I pull the PCV valve out while at idle.  Using some oil and rough idle are indicators of a possible PCV issue, vacuum line issue... or EGR valve issue.  

You guys have any thoughts or experience with this?

Oh yeah, and the EGR valve is conveniently located (NOT!) in the rear of the engine on the lower side of the intake.  You have to be a freakin contortionist to get to it.

I have the same RARE low idle when I hit the clutch after a stop, but I've never worried too much about it.  I figure it might be the IAC valve being a little slow to open up when the throttle closes.  I haven't noticed it using oil like that, but I don't check it often enough to see an issue within just a few hundred miles (shame on me).

Speaking of the EGR valve, though, has anyone noticed that after a few seconds at full throttle, the 2.0 seems to get a "turbo" boost?  I've noticed it very predictably when getting on the freeway or passing someone.  The only thing I can figure is that the computer is seeing that you're demanding maximum power, so it temporarily shuts off EGR so the engine can pull maximum fresh air into the intake (instead of already-used air).  Either that, or it momentarily switches the fuel map up a notch so it runs a little richer.  I've never been able to find it documented, but it sure is nice when it happens.  ;-)

Good to hear that your CEL is off and (more importantly) that your mileage is coming back to normal.

I think a part of the "butt-dyno kick" you are feeling is simply that little 2 Liter "coming alive" into the  meat of its actual power band.  I don't have my references in front of me, but I recall the 2 liter actually makes its peak power around the 4000 RPM... maybe 4200 RPM.  We typically poke around town and on the country roads and never really punch it into the main power band so when we do... it feels like a turbo boost.

These 2 liters are sweet little engines.  I love'em.

Reference the occasional rough idle, I replaced my IAC a year ago when I experienced some difficult cold weather starting.  Once I replaced it... no more cold weather starting problems.  They are salty though.

That's why I was wondering if anyone had experienced any EGR carboning issues on their truck.  The EGR is electronic on these, no vacuum lines, but I supposed they could still clog with carbon.  So far my CEL has not returned.  I am continually checking my MPG at fuel ups to see if the MPGs will continue to climb back up to normal range.