I have a 95 Nissan D21 Hardbody, V6, 3.0 4x4, 169,000 miles. I have over 10,000.00 in it since June of 2019. It is currently cutting out, no power, 40mph if I am lucky by the time I get to the top of a hill, check engine light comes on & then goes off, using gas like there is no tomorrow. Also speedometer is sporadically not working. Supposed to have my son cut out the Catalytic Converter Sunday & straight pipe it. Please any correct guidance would be so greatly appreciated.