You may have already done so, but worth checking the vaccum through-passage in the intake incase that clogged? Thats what caused my 401. I don't recall if that could also cause a 402.
'97 lx450, 170k, factory lockers, ome 850/863, 285's, 4 working doors(1 more than the old fj55 )
'74 project pig (sold