Smoke when going down hill. Also rough idle and cold runing

[dayofthejackal]

My car ran perfectly with just a stage 1 remap then I did a stage 2 conversion on it and now I have loads of grey and blue smoke coming out of the exhaust but only when going down a hill and only at low (below 2K) revs, also if I brake hard which clears on the flat after a few seconds.
Normal driving on the flat or going up hill is fine, no smoke on idle or when booting it.
AND
Since stage 2 I've also got a very rough idle, sound like I'm revving the car.
AND
The power cuts out between 1.2k and 1.8k revs especially when cold, it's un-drivable cold.

No codes showing, I did a home made smoke test and no vacuum leeks showed.

Smoke = Turbo or Rings?
Idle and running = ???

 

[s3dave]

Breather system blocked? do you have a catch can?

 

[dayofthejackal]

I fitted a new catch can with new pipes about 500 miles after doing the conversion. I had a 15mm and fitted a 19mm.

 

[s3dave]

just let it vent to atmosphere and see if it helps,

 

[dayofthejackal]

Tried vent to atmosphere and no difference.

Could the power cuts be something to do with wastegate actuator. When the power cuts I can hear a sound like air dumping or turbo spooling but its not the recirc' valve, tested without it.