Pulsation?

[Jettage1]

So what would cause a pulsation felt in your forward motion under light/moderate acceleration?  It is not violent bucking at all, just a sort of forward / rearward motion, or I guess you'd say a rhythmic lack of consistency or smoothness in power delivery.  The car didn't always do this, so I know it's not normal.  

The IP is bolted down tight, and I believe the clutch is fine.  Timing is around 1.00 and IP & injectors are new.  Is there some IP adjustment that would create or eliminate this sort of condition?  Maybe some sort of a fuel delivery issue?

Thanks guys.

[Duster 5.9]

have you changed the filter lately? do you see any bubbles inline? anything leaking?

[Jettage1]

Nothing's leaking, haven't seen bubbles, pump bolts are tight.  Will inspect motor mounts.

Haven't changed filter in awhile...  maybe that's a candidate.

Someone also suggested that excessive crankcase oil being burned (either from blowby or from the turbo) could lead to inconsistent behavior since the engine wouldn't be entirely controlled by the IP...  

I disconnected the crankcase-to-intake return but no difference.  Since I do have some gray smoke under load I'm considering a turbo rebuild...