ok fixed both codes the po430 i replaced the front o2 sensor that didnt work sooo i ordered a magnaflow catalytic convertor and welded that in...that fixed that.
the po401 code was kinda tricky..replaced the map sensor,and then the egr valve,checked the pipe from the egr valve to the exhaust manifold for blockage.that is a ll the manual tells ya to do so i googled "isuzu 3.5 dtc po401"and low and behold.there is a pipe/tube inside the intake(behind the throttle body)that supplies the egr with vacuum.it was clogged solid...cleaned it out with carb cleaner,hanger,and a blow gun.
both codes gone!!!!!