I just wanted to thank all the guys and Gals that spend there time adding there experiences of Alfa mechanical and electrical foybles on the forum. I have just fixed my 04 156 1.9 JTD, myself. I have a little bit more than average mechanical know how. But I could not do it without learning from other peoples lessons. Thank you.
Lack of umphh and a sucking noise under bonnet progressed in to a no umph and clouds of smoke on acceleration.
Examined all hoses as suggested found split in top air hose connecting intercooler with the intake manifold.
Repaired said hose.
Hose repair failed. (surprising how much pressure there is in that hose)
replaced hose £54 inc VAT and two clips
now now low rev umphh!
Suspected EGR valve problem.
Strip and cleaned (solid caked up in soot) as advised on forum
now "Motor Control Failure" (now it decides to tell me somethings wrong, now I have fixed it)
on-off x4 system good again and all back to wonderful working order.
Left wondering if EGR soot caused hose to burst or Hose burst caused EGR soot?
Either way if one goes check the other IMO.
Once again thank you technical forum!