Got a 1.8tqs that boosts well in all gears except for 3rd.
Boost build nicely from 2000 to about 3500/3800rpm and then the boost drops off (like someone has thrown out an anchor) then picks up again.
Car is fine in 2nd, 4th and 5th....
Just put on a Forge 007p and this hasn't cured it.
Wild stabs in the dark?