Tps sensor and mass air flow senspr low voltage. Help gurus.

So I did a cat delete replaced all spark plugs
and wires now have a tps sensor low
voltage and mass air flow sensor low
voltage and random multiple misfires.
Could it be something simple or am I
tearing into the firewall to find the break? I
can unplug both sensors and the car stays
running plus two others idle sensor maybe
and another. 2002 grand prix 3100 series