Audi A4 tdi engine intermittent power loss producing black/grey smoke

HELP! Somebody- My 2005 AUDI A4 intermittently looses power while produces black/ grey smoke with no fault code reported. Renewed MAF and MAP sensor, while
reset ECU by removing battery earth for half hour. Checked ECU for water ingress- none found. Cleaned dirty EGR valve and reset 'Service' indicator, occasionally get a load of rubbish random fault codes that clear as easily they come, help somebody please!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.