What part of South Africa are you in?
Welcome to the site.....best site for CRD issues.
The Dealers here in SA are pretty useless!
First make sure you read Sams Noob Guide...covers a lot of common problems.
Smoking and lack of power can be torn or holed CAC hoses...I have had this. You need to pull them off and examine them carefully for tears etc. Note how they are aligned before removing them so that you put them back in place with the correct rotation before tightening up the hoses clamps.
Most overseas owners use Silicon Samco hoses...last much longer and come in different colors.....I just replaced with OEM some years ago. My one clamp came loose on a long trip and the Jeep slowed down drastically and hade no power so check that as well.
Any fuel supply problems do not usually post any codes so make sure you know how to bleed air out of the system and make sure you have a clean fuel filter. My old fuel filter would cause my old 2002 Export 2.5 CRD to suddenly cut out completely...a few seconds later it would be able to re-start.
Elephant hose refers to a pipe directing crankcase pressure/oil to the ground or to a catch-can rather than feed it back into the intake where it soils the inside of the CAC hoses with oil...this is a mod that I have not bothered with.
Yesterday I removed the round black plastic box, CCV valve, on top of the cam cover which feeds the crank gases back into the system...leaks around that area are not uncommon....gave the black box a good clean inside.
Smoke and low power can also be the MAP sensor needs cleaning...I cleaned mine yesterday due to this problem.
Sams Guide covers this well....just treat the MAP sensor with care....use Brake Cleaner spray to spray it clean.
Also maybe add a good make of Diesel Fuel Injector Cleaner to your next tank of fuel....I only use Sasol diesel as it is the cleanest at 10 ppm Sulphur!
If need be try a different Dealer...next dealer may find some stored error codes!
The Crankshaft Sensor and the Camshaft sensor are known to have give problems...I have not yet had any problems.
It is difficult to get 2007 KJ Service Manuals but download the 2006 Manuals here..should be close enough!
http://www.colorado4wheel.com/manuals/Jeep/KJ