Rough idle 1985 Alfa 90 2.5 v6

[The Count]

My 85 Alfa 90 V6 tends to idle quite roughly especially when cold but even when warmed up it's still rough and tacho reads only about 600-800 rpm
On the road it's quite smooth so only at idle do I Gert that roughness.
Any ideas?
Nick

[V AR 164]

I had this happen to my other 164 a while back. Found out it was a perished vacuum hose running off the plenum (intake manifold) letting in air the maf didn't read.
I would check all vacuum lines first of all.

Andrew.

[Sheldon McIntosh]

Agree with that, definitely an air-leak somewhere.  The "accordion" hose from the filter to the plenum is notorious for leaking.  Seal it up with shoo-goo or something similar