Reduce TD continuous table. If you never reduced it from stock, start out by multiplying by about 0.6. Then if it still oscillates, multiply all cells by 0.9 again and again until it's stable. This will mean you have to have your target boost setup for your boost ramp, or you'll have an overboost spike, as it will be slower to clamp down on boost as it spools up.
Oscillation means that it's overadjusting and never able to settle down to target, so you need to reduce how much it adjusts.