Please, help. Not long ago, car was running beautifully, smooth and powerful with clean plugs. Then, I put in a Dawes Device boost controller and had clouds of thick black smoke coming out of the exhaust pipe in direct relation to acceleration. Plugs were covered with black velvet like powdery soot. All hoses and most ignition and injection components were new and all checked out for speficied voltage and resistance parameters. O2 sensor, FPR and coil were not new, but still checked out OK. I have now put in new O2 sensor and FPR. Still, I get overly rich fuel/air with Dawes Device boost controller.

(1) What is telling ECU to enrich fuel/air?
(2) Can the cure be raised boost to also raise air/fuel, perhaps checked with air/fuel meter, until plugs burn clean?
(3) Can engine mechanically stand 12 psi of boost, perhaps a bit more, with 150,000 miles in original bottom end, and 60,000 miles in over five years old head and turbo, as long as air/fuel is not too lean?