[MR2] MR2 Turbo Surg

[Dennis McFayden]

My '91 turbo has a problem. while the boost pressure is up if a person eases up on the accelerator there is an engine surge. This is a pretty big surge. It doesn't seem to happen all of the time but always during boost. 
 
Any ideas? I am trying to get more data on the exact conditions for this surge. The car is now pretty much stock. The prior configuration had a HKS blow-out valve. The surge also existed with that valve. 
 
My suspicion is the throttle position sensor adjustment. 
 
Dennis