Ka-t Sudden problems. help diagnose

[bdeisle]

all of a sudden car starts sputtering under boost. a little back fire.. new plugs new wires. new cap and rotor. fuel pressure is all right.. after i changed the plug wires , cap/rotor, felt alot better driving. but now say when i "blow off" or give it some gas my HKS turbo timer. starts counting down like its about to shut off. any IDEAS would be great! on how to fix or what to look at now