Kia Carens UN 2.0 CRDI- Problems

Hello everyone,

I have bought a used 2006 Carens 2.0 CRDI - 140HP diesel Automatic and I'm pretty happy with what it offers for the price but there are several problems I noticed even tho it had service manual and regular checks.

1. There is a strange phenomenon happening when I'm driving at around 50km/h with constant acceleration. The rpm is about 1-2k but then it gets out of gear, drops rpm and starts to accelerate again. This happens over and over until the oil warms up (I think). There is no problem when I'm flooring it at any speed and it pulls hard and smooth.

2. Cruise control does not engage regardless of what I do. The cruise sign on dashboard doesn't turn on.

For point 2 I have managed to turn it on after I've erased the DCT codes. The light came up but as soon as I've started the car it went off and never worked again.

As I've mentioned the DCT, I should also mention the codes associated(read with a cheap OBD2 module). There was also a check engine light that sometimes is up but mostly it stays off.

P0700 - Transmission control Module MIL requested
0741 - Torque Converter Clutch Circuit Performance or Stuck Off
OOE4 - Unknown Trouble Code
1406 - Custom Error Code

After I've cleared all codes, the only one that stays is 1406.

As I've read 1406 is related to EGR valve. I'm gonna clean it next week just to be sure.

Does anyone have any experience with it? Anything I should be looking for?